if( pExpr->op==TK_TRIGGER 
   && pExpr->iColumn==p->iCol 
   && pWalker->pParse->pTriggerTab==p->pTab
  ){
    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
  }else if( pExpr->op==TK_COLUMN 
   && pExpr->iColumn==p->iCol 
   && ALWAYS(pExpr->eX==EX_Tab)
   && p->pTab==pExpr->x.pTab
  ){
    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
  }
  return WRC_Continue;
}

/*

}

/*
** Walker expression callback used by "RENAME TABLE". 
*/
static int renameTableExprCb(Walker *pWalker, Expr *pExpr){
  RenameCtx *p = pWalker->u.pRename;
  if( pExpr->op==TK_COLUMN 
   && ALWAYS(pExpr->eX==EX_Tab)
   && p->pTab==pExpr->x.pTab
  ){
    renameTokenFind(pWalker->pParse, p, (void*)&pExpr->x.pTab);
  }
  return WRC_Continue;
}

/*
** Walker select callback used by "RENAME TABLE". 
*/

        pExpr->op = TK_NULL;
      }else{
        sqlite3ErrorMsg(pFix->pParse, "%s cannot use variables", pFix->zType);
        return 1;
      }
    }
    if( ExprHasProperty(pExpr, EP_TokenOnly|EP_Leaf) ) break;
    switch( pExpr->eX ){
      case EX_Select: {
        if( sqlite3FixSelect(pFix, pExpr->x.pSelect) ) return 1;
        break;
      }
      case EX_List: {
        if( sqlite3FixExprList(pFix, pExpr->x.pList) ) return 1;
        break;
      }
      case EX_Right: {
        if( sqlite3FixExpr(pFix, pExpr->x.pRight) ) return 1;
        break;
      }
    }
    pExpr = pExpr->pLeft;
  }
  return 0;
}
int sqlite3FixExprList(
  DbFixer *pFix,     /* Context of the fixation */

    }else{
      int i;
      for(i=0; i<pPk->nKeyCol; i++){
        Expr *p = sqlite3Expr(db, TK_ID, pTab->aCol[pPk->aiColumn[i]].zName);
        pEList = sqlite3ExprListAppend(pParse, pEList, p);
      }
      pLhs = sqlite3PExpr(pParse, TK_VECTOR, 0, 0);
      sqlite3PExprAddExprList(pParse, pLhs, pEList);


    }
  }

  /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
  ** and the SELECT subtree. */
  pSrc->a[0].pTab = 0;
  pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);

*/
char sqlite3ExprAffinity(Expr *pExpr){
  int op;
  pExpr = sqlite3ExprSkipCollate(pExpr);
  if( pExpr->flags & EP_Generic ) return 0;
  op = pExpr->op;
  if( op==TK_SELECT ){
    assert( pExpr->eX==EX_Select );
    return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
  }
  if( op==TK_REGISTER ) op = pExpr->op2;
#ifndef SQLITE_OMIT_CAST
  if( op==TK_CAST ){
    assert( !ExprHasProperty(pExpr, EP_IntValue) );
    return sqlite3AffinityType(pExpr->u.zToken, 0);
  }
#endif
  if( (op==TK_AGG_COLUMN || op==TK_COLUMN)
   && ALWAYS(pExpr->eX==EX_Tab) && pExpr->x.pTab ){
    return sqlite3TableColumnAffinity(pExpr->x.pTab, pExpr->iColumn);
  }
  if( op==TK_SELECT_COLUMN ){
    assert( pExpr->pLeft->eX==EX_Select );
    return sqlite3ExprAffinity(
        pExpr->pLeft->x.pSelect->pEList->a[pExpr->iColumn].pExpr
    );
  }
  return pExpr->affinity;
}

/*
** Skip over any TK_COLLATE operators and any unlikely()
** or likelihood() function at the root of an expression.
*/
Expr *sqlite3ExprSkipCollate(Expr *pExpr){
  while( pExpr && ExprHasProperty(pExpr, EP_Skip) ){
    if( ExprHasProperty(pExpr, EP_Unlikely) ){
      assert( pExpr->eX==EX_List );
      assert( pExpr->x.pList->nExpr>0 );
      assert( pExpr->op==TK_FUNCTION );
      pExpr = pExpr->x.pList->a[0].pExpr;
    }else{
      assert( pExpr->op==TK_COLLATE );
      pExpr = pExpr->pLeft;
    }

  CollSeq *pColl = 0;
  Expr *p = pExpr;
  while( p ){
    int op = p->op;
    if( p->flags & EP_Generic ) break;
    if( (op==TK_AGG_COLUMN || op==TK_COLUMN
          || op==TK_REGISTER || op==TK_TRIGGER)
     && p->eX==EX_Tab
     && p->x.pTab!=0
    ){
      /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
      ** a TK_COLUMN but was previously evaluated and cached in a register */
      int j = p->iColumn;
      if( j>=0 ){
        const char *zColl = p->x.pTab->aCol[j].zColl;
        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
      }
      break;
    }
    if( op==TK_CAST || op==TK_UPLUS ){
      p = p->pLeft;
      continue;
    }
    if( op==TK_COLLATE || (op==TK_REGISTER && p->op2==TK_COLLATE) ){
      pColl = sqlite3GetCollSeq(pParse, ENC(db), 0, p->u.zToken);
      break;
    }
    if( p->flags & EP_Collate ){
      if( p->pLeft && (p->pLeft->flags & EP_Collate)!=0 ){
        p = p->pLeft;
      }else{
        Expr *pNext = 0;


        /* p->flags holds EP_Collate and p->pLeft->flags does not.  And
        ** p->x.pSelect cannot.  So if p->x.pLeft exists, it must hold at
        ** least one EP_Collate. Thus the following two ALWAYS. */
        if( p->eX==EX_List ){
          int i;
          for(i=0; ALWAYS(i<p->x.pList->nExpr); i++){
            if( ExprHasProperty(p->x.pList->a[i].pExpr, EP_Collate) ){
              pNext = p->x.pList->a[i].pExpr;
              break;
            }
          }
        }else if( p->eX==EX_Right ){
          pNext = p->x.pRight;
        }
        p = pNext;
      }
    }else{
      break;
    }
  }

static char comparisonAffinity(Expr *pExpr){
  char aff;
  assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||
          pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||
          pExpr->op==TK_NE || pExpr->op==TK_IS || pExpr->op==TK_ISNOT );
  assert( pExpr->pLeft );
  aff = sqlite3ExprAffinity(pExpr->pLeft);
  if( pExpr->eX==EX_Right ){
    aff = sqlite3CompareAffinity(pExpr->x.pRight, aff);
  }else if( pExpr->eX==EX_Select ){
    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
  }else if( aff==0 ){
    aff = SQLITE_AFF_BLOB;
  }
  return aff;
}

** If the left hand expression has a collating sequence type, then it is
** used. Otherwise the collation sequence for the right hand expression
** is used, or the default (BINARY) if neither expression has a collating
** type.
**
** Argument pRight (but not pLeft) may be a null pointer. In this case,
** it is not considered.
**
** The second form (sqlite3BinaryExprCollSeq()) uses the Expr.pLeft
** and Expr.x.pRight pointer from the second argument instead of separate
** pointers.
*/
CollSeq *sqlite3ComparisonCollSeq(
  Parse *pParse, 
  Expr *pLeft, 
  Expr *pRight
){
  CollSeq *pColl;
  assert( pLeft );
  if( pLeft->flags & EP_Collate ){
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
  }else if( pRight && (pRight->flags & EP_Collate)!=0 ){
    pColl = sqlite3ExprCollSeq(pParse, pRight);
  }else{
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
    if( !pColl ){
      pColl = sqlite3ExprCollSeq(pParse, pRight);
    }
  }
  return pColl;
}
CollSeq *sqlite3ComparisonExprCollSeq(Parse *pParse, Expr *pExpr){
  if( pExpr->eX==EX_Right ){
    return sqlite3ComparisonCollSeq(pParse, pExpr->pLeft, pExpr->x.pRight);
  }else{
    return sqlite3ComparisonCollSeq(pParse, pExpr->pLeft, 0);
  }
}

/*
** Generate code for a comparison operator.
*/
static int codeCompare(
  Parse *pParse,    /* The parsing (and code generating) context */
  Expr *pLeft,      /* The left operand */
  Expr *pRight,     /* The right operand */
  int opcode,       /* The comparison opcode */
  int in1, int in2, /* Register holding operands */
  int dest,         /* Jump here if true.  */
  int jumpIfNull    /* If true, jump if either operand is NULL */
){
  int p5;
  int addr;
  CollSeq *p4;

  p4 = sqlite3ComparisonCollSeq(pParse, pLeft, pRight);
  p5 = binaryCompareP5(pLeft, pRight, jumpIfNull);
  addr = sqlite3VdbeAddOp4(pParse->pVdbe, opcode, in2, dest, in1,
                           (void*)p4, P4_COLLSEQ);
  sqlite3VdbeChangeP5(pParse->pVdbe, (u8)p5);
  return addr;
}

Expr *sqlite3ExprForVectorField(
  Parse *pParse,       /* Parsing context */
  Expr *pVector,       /* The vector.  List of expressions or a sub-SELECT */
  int iField           /* Which column of the vector to return */
){
  Expr *pRet;
  if( pVector->op==TK_SELECT ){
    assert( pVector->eX==EX_Select );
    /* The TK_SELECT_COLUMN Expr node:
    **
    ** pLeft:           pVector containing TK_SELECT.  Not deleted.
    ** pRight:          not used.  But recursively deleted.
    ** iColumn:         Index of a column in pVector
    ** iTable:          0 or the number of columns on the LHS of an assignment
    ** pLeft->iTable:   First in an array of register holding result, or 0

  Expr *pExpr,          /* The comparison operation */
  int dest,             /* Write results into this register */
  u8 op,                /* Comparison operator */
  u8 p5                 /* SQLITE_NULLEQ or zero */
){
  Vdbe *v = pParse->pVdbe;
  Expr *pLeft = pExpr->pLeft;
  Expr *pRight = pExpr->x.pRight;
  int nLeft = sqlite3ExprVectorSize(pLeft);
  int i;
  int regLeft = 0;
  int regRight = 0;
  u8 opx = op;
  int addrDone = sqlite3VdbeMakeLabel(v);

**
** Also propagate EP_Propagate flags up from Expr.x.pList to Expr.flags,
** if appropriate.
*/
static void exprSetHeight(Expr *p){
  int nHeight = 0;
  heightOfExpr(p->pLeft, &nHeight);
  switch( p->eX ){
    case EX_Select: {
      heightOfSelect(p->x.pSelect, &nHeight);
      break;
    }
    case EX_List: {
      heightOfExprList(p->x.pList, &nHeight);
      p->flags |= EP_Propagate & sqlite3ExprListFlags(p->x.pList);
      break;
    }
    case EX_Right: {
      heightOfExpr(p->x.pRight, &nHeight);
      break;
    }
  }
  p->nHeight = nHeight + 1;
}

/*
** Set the Expr.nHeight variable using the exprSetHeight() function. If
** the height is greater than the maximum allowed expression depth,
** leave an error in pParse.
**
** Also propagate all EP_Propagate flags from the Expr.x.pList into
** Expr.flags. 
*/
void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p){
  if( p==0 || pParse->nErr ) return;
  exprSetHeight(p);
  sqlite3ExprCheckHeight(pParse, p->nHeight);
}

/*
** Return the maximum height of any expression tree referenced
** by the select statement passed as an argument.
*/
int sqlite3SelectExprHeight(Select *p){
  int nHeight = 0;
  heightOfSelect(p, &nHeight);
  return nHeight;
}
#else /* ABOVE:  Height enforcement enabled.  BELOW: Height enforcement off */
/*
** Propagate all EP_Propagate flags from the Expr.x.pList into
** Expr.flags. 
*/
void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p){
  if( p && p->eX==EX_List ){
    p->flags |= EP_Propagate & sqlite3ExprListFlags(p->x.pList);
  }
}
#define exprSetHeight(y)
#endif /* SQLITE_MAX_EXPR_DEPTH>0 */

/*

){
  if( pRoot==0 ){
    assert( db->mallocFailed );
    sqlite3ExprDelete(db, pLeft);
    sqlite3ExprDelete(db, pRight);
  }else{
    if( pRight ){
      assert( pRoot->eX==EX_None );
      pRoot->x.pRight = pRight;
      pRoot->eX = EX_Right;
      pRoot->flags |= EP_Propagate & pRight->flags;
    }
    if( pLeft ){
      pRoot->pLeft = pLeft;
      pRoot->flags |= EP_Propagate & pLeft->flags;
    }
    exprSetHeight(pRoot);

}

/*
** Add pSelect to the Expr.x.pSelect field.  Or, if pExpr is NULL (due
** do a memory allocation failure) then delete the pSelect object.
*/
void sqlite3PExprAddSelect(Parse *pParse, Expr *pExpr, Select *pSelect){
  if( pExpr && pSelect ){
    assert( pExpr->eX==EX_None );
    pExpr->eX = EX_Select;
    pExpr->x.pSelect = pSelect;
    ExprSetProperty(pExpr, EP_Subquery);
    sqlite3ExprSetHeightAndFlags(pParse, pExpr);
  }else{
    assert( pParse->db->mallocFailed );
    sqlite3SelectDelete(pParse->db, pSelect);
  }
}

/*
** Add ExprList to the Expr.x.pList field.  Or, if pExpr is NULL (due
** do a memory allocation failure) then delete the pSelect object.
*/
void sqlite3PExprAddExprList(Parse *pParse, Expr *pExpr, ExprList *pList){
  if( pExpr && pList ){
    assert( pExpr->eX==EX_None );
    pExpr->eX = EX_List;
    pExpr->x.pList = pList;
    /* sqlite3ExprSetHeightAndFlags(pParse, pExpr); // done by caller */
  }else{
    assert( pParse->db->mallocFailed );
    sqlite3ExprListDelete(pParse->db, pList);
  }
}


/*
** If the expression is always either TRUE or FALSE (respectively),
** then return 1.  If one cannot determine the truth value of the
** expression at compile-time return 0.
**

  if( pNew==0 ){
    sqlite3ExprListDelete(db, pList); /* Avoid memory leak when malloc fails */
    return 0;
  }
  if( pList && pList->nExpr > pParse->db->aLimit[SQLITE_LIMIT_FUNCTION_ARG] ){
    sqlite3ErrorMsg(pParse, "too many arguments on function %T", pToken);
  }
  assert( pNew->eX==EX_None );
  if( pList ){
    pNew->eX = EX_List;
    pNew->x.pList = pList;
  }
  ExprSetProperty(pNew, EP_HasFunc);

  sqlite3ExprSetHeightAndFlags(pParse, pNew);
  if( eDistinct==SF_Distinct ) ExprSetProperty(pNew, EP_Distinct);
  return pNew;
}

/*
** Assign a variable number to an expression that encodes a wildcard

/*
** Recursively delete an expression tree.
*/
static SQLITE_NOINLINE void sqlite3ExprDeleteNN(sqlite3 *db, Expr *p){
  assert( p!=0 );
  /* Sanity check: Assert that the IntValue is non-negative if it exists */
  assert( !ExprHasProperty(p, EP_IntValue) || p->u.iValue>=0 );
  assert( p->eX!=EX_Select || p->x.pSelect!=0 );
  assert( p->eX!=EX_List || p->x.pList!=0 );
#ifdef SQLITE_DEBUG
  if( ExprHasProperty(p, EP_Leaf) && !ExprHasProperty(p, EP_TokenOnly) ){
    assert( p->pLeft==0 );
    assert( p->eX==EX_None || p->eX==EX_Tab );
  }
  if( !ExprHasProperty(p, EP_TokenOnly) ){
    assert( p->op!=TK_FUNCTION || p->pLeft==0 );
  }
  if( !ExprHasProperty(p, (EP_TokenOnly|EP_Reduced)) ){
    assert( p->pWin==0 || p->pLeft==0 );
    assert( p->pWin==0 || p->op==TK_FUNCTION );
  }
#endif
  if( !ExprHasProperty(p, (EP_TokenOnly|EP_Leaf)) ){


    if( p->pLeft && p->op!=TK_SELECT_COLUMN ) sqlite3ExprDeleteNN(db, p->pLeft);
    switch( p->eX ){

      case EX_Select: {
        sqlite3SelectDelete(db, p->x.pSelect);
        break;
      }
      case EX_List: {
        sqlite3ExprListDelete(db, p->x.pList);
        break;
      }
      case EX_Right: {
        sqlite3ExprDelete(db, p->x.pRight);
        break;
      }
    }
    if( !ExprHasProperty(p, EP_Reduced) ){
      sqlite3WindowDelete(db, p->pWin);
    }
  }
  if( ExprHasProperty(p, EP_MemToken) ) sqlite3DbFree(db, p->u.zToken);
  if( !ExprHasProperty(p, EP_Static) ){
    sqlite3DbFreeNN(db, p);
  }
}
void sqlite3ExprDelete(sqlite3 *db, Expr *p){
  if( p ) sqlite3ExprDeleteNN(db, p);
}

void sqlite3ExprClearXUnion(sqlite3 *db, Expr *p){
  switch( p->eX ){
    case EX_Select: {
      sqlite3SelectDelete(db, p->x.pSelect);
      break;
    }
    case EX_List: {
      sqlite3ExprListDelete(db, p->x.pList);
      break;
    }
    case EX_Right: {
      sqlite3ExprDelete(db, p->x.pRight);
      break;
    }
  }
  p->eX = EX_None;
}
void sqlite3ExprAddTab(sqlite3 *db, Expr *pExpr, Table *pTab){
  sqlite3ExprClearXUnion(db, pExpr);
  pExpr->eX = EX_Tab;
  pExpr->x.pTab = pTab;
}

/*
** Return the number of bytes allocated for the expression structure 
** passed as the first argument. This is always one of EXPR_FULLSIZE,
** EXPR_REDUCEDSIZE or EXPR_TOKENONLYSIZE.
*/
static int exprStructSize(Expr *p){

  ){
    nSize = EXPR_FULLSIZE;
  }else{
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    assert( !ExprHasProperty(p, EP_FromJoin) ); 
    assert( !ExprHasProperty(p, EP_MemToken) );
    assert( !ExprHasProperty(p, EP_NoReduce) );
    if( p->pLeft || p->eX!=EX_None ){
      nSize = EXPR_REDUCEDSIZE | EP_Reduced;
    }else{

      nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
    }
  }
  return nSize;
}

/*

** descended from the Expr.x.pList or Expr.x.pSelect variables).
*/
static int dupedExprSize(Expr *p, int flags){
  int nByte = 0;
  if( p ){
    nByte = dupedExprNodeSize(p, flags);
    if( flags&EXPRDUP_REDUCE ){
      nByte += dupedExprSize(p->pLeft, flags);
      if( p->eX==EX_Right ) nByte += dupedExprSize(p->x.pRight, flags);
    }
  }
  return nByte;
}

/*
** This function is similar to sqlite3ExprDup(), except that if pzBuffer 
** is not NULL then *pzBuffer is assumed to point to a buffer large enough 
** to store the copy of expression p, the copies of p->u.zToken
** (if applicable), and the copies of the p->pLeft and p->x.pRight expressions,
** if any. Before returning, *pzBuffer is set to the first byte past the
** portion of the buffer copied into by this function.
*/
static Expr *exprDup(sqlite3 *db, Expr *p, int dupFlags, u8 **pzBuffer){
  Expr *pNew;           /* Value to return */
  u8 *zAlloc;           /* Memory space from which to build Expr object */
  u32 staticFlag;       /* EP_Static if space not obtained from malloc */

      }
    }

    /* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
    pNew->flags &= ~(EP_Reduced|EP_TokenOnly|EP_Static|EP_MemToken);
    pNew->flags |= nStructSize & (EP_Reduced|EP_TokenOnly);
    pNew->flags |= staticFlag;
    assert( pNew->eX==p->eX );
    assert( pNew->eV==p->eV );

    /* Copy the p->u.zToken string, if any. */
    if( nToken ){
      char *zToken = pNew->u.zToken = (char*)&zAlloc[nNewSize];
      memcpy(zToken, p->u.zToken, nToken);
    }

    if( 0==((p->flags|pNew->flags) & (EP_TokenOnly|EP_Leaf)) ){
      /* Fill in the pNew->x.pSelect or pNew->x.pList member. */
      switch( p->eX ){
        case EX_Select: {
          assert( pNew->eX==EX_Select );
          pNew->x.pSelect = sqlite3SelectDup(db, p->x.pSelect, dupFlags);
          if( pNew->x.pSelect==0 ) pNew->eX = EX_None;
          break;
        }
        case EX_List: {
          assert( pNew->eX==EX_List );
          pNew->x.pList = sqlite3ExprListDup(db, p->x.pList, dupFlags);
          if( pNew->x.pList==0 ) pNew->eX = EX_None;
          break;
        }
      }
    }

    /* Fill in pNew->pLeft and pNew->x.pRight. */
    if( ExprHasProperty(pNew, EP_Reduced|EP_TokenOnly) ){
      zAlloc += dupedExprNodeSize(p, dupFlags);
      if( !ExprHasProperty(pNew, EP_TokenOnly|EP_Leaf) ){
        pNew->pLeft = p->pLeft ?
                      exprDup(db, p->pLeft, EXPRDUP_REDUCE, &zAlloc) : 0;
        if( p->eX==EX_Right ){
          pNew->x.pRight = exprDup(db, p->x.pRight, EXPRDUP_REDUCE, &zAlloc);
        }
      }
      if( pzBuffer ){
        *pzBuffer = zAlloc;
      }
    }else{
#ifndef SQLITE_OMIT_WINDOWFUNC
      if( ExprHasProperty(p, EP_Reduced|EP_TokenOnly) ){
        pNew->pWin = 0;
      }else{
        pNew->pWin = sqlite3WindowDup(db, pNew, p->pWin);
      }
#endif /* SQLITE_OMIT_WINDOWFUNC */
      if( !ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
        if( pNew->op==TK_SELECT_COLUMN ){
          pNew->pLeft = p->pLeft;
          assert( p->iColumn==0 || p->eX!=EX_Right );
          /* OLD: assert( p->pRight==0  || p->x.pRight==p->pLeft ); */
        }else{
          pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
        }
        if( p->eX==EX_Right ){
          pNew->x.pRight = sqlite3ExprDup(db, p->x.pRight, 0);
          if( pNew->x.pRight==0 ) pNew->eX = EX_None;
        }
      }
    }
  }
  return pNew;
}

/*

    pItem->pExpr = sqlite3ExprDup(db, pOldExpr, flags);
    if( pOldExpr 
     && pOldExpr->op==TK_SELECT_COLUMN
     && (pNewExpr = pItem->pExpr)!=0 
    ){
      assert( pNewExpr->iColumn==0 || i>0 );
      if( pNewExpr->iColumn==0 ){
        assert( pOldExpr->pLeft==pOldExpr->x.pRight );
        pPriorSelectCol = pNewExpr->pLeft = pNewExpr->x.pRight;
      }else{
        assert( i>0 );
        assert( pItem[-1].pExpr!=0 );
        assert( pNewExpr->iColumn==pItem[-1].pExpr->iColumn+1 );
        assert( pPriorSelectCol==pItem[-1].pExpr->pLeft );
        pNewExpr->pLeft = pPriorSelectCol;
      }

  if( !db->mallocFailed && pExpr->op==TK_SELECT && ALWAYS(pList!=0) ){
    Expr *pFirst = pList->a[iFirst].pExpr;
    assert( pFirst!=0 );
    assert( pFirst->op==TK_SELECT_COLUMN );
     
    /* Store the SELECT statement in pRight so it will be deleted when
    ** sqlite3ExprListDelete() is called */
    assert( pFirst->eX==EX_None );
    pFirst->x.pRight = pExpr;
    pFirst->eX = EX_Right;
    pExpr = 0;

    /* Remember the size of the LHS in iTable so that we can check that
    ** the RHS and LHS sizes match during code generation. */
    pFirst->iTable = pColumns->nId;
  }

      if( sqlite3IsBinary(pColl) ){
        return WRC_Prune;
      }
    }
  }

  /* Check if pExpr is a sub-select. If so, consider it variable. */
  if( pExpr->eX==EX_Select ){
    pWalker->eCode = 0;
    return WRC_Abort;
  }

  return exprNodeIsConstant(pWalker, pExpr);
}

  switch( op ){
    case TK_INTEGER:
    case TK_STRING:
    case TK_FLOAT:
    case TK_BLOB:
      return 0;
    case TK_COLUMN:
      assert( p->eX==EX_Tab );
      return ExprHasProperty(p, EP_CanBeNull) ||
             p->x.pTab==0 ||  /* Reference to column of index on expression */
             (p->iColumn>=0 && p->x.pTab->aCol[p->iColumn].notNull==0);
    default:
      return 1;
  }
}

/*
** Return TRUE if the given expression is a constant which would be

#ifndef SQLITE_OMIT_SUBQUERY
static Select *isCandidateForInOpt(Expr *pX){
  Select *p;
  SrcList *pSrc;
  ExprList *pEList;
  Table *pTab;
  int i;
  if( pX->eX!=EX_Select ) return 0;      /* Not a subquery */
  if( ExprHasProperty(pX, EP_VarSelect) ){
    return 0;                            /* Correlated subq */
  }
  p = pX->x.pSelect;
  if( p->pPrior ) return 0;              /* Not a compound SELECT */
  if( p->selFlags & (SF_Distinct|SF_Aggregate) ){
    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
    return 0; /* No DISTINCT keyword and no aggregate functions */
  }

/*
** The argument is an IN operator with a list (not a subquery) on the 
** right-hand side.  Return TRUE if that list is constant.
*/
static int sqlite3InRhsIsConstant(Expr *pIn){
  Expr *pLHS;
  int res;
  assert( pIn->eX!=EX_Select );
  pLHS = pIn->pLeft;
  pIn->pLeft = 0;
  res = sqlite3ExprIsConstant(pIn);
  pIn->pLeft = pLHS;
  return res;
}
#endif

  mustBeUnique = (inFlags & IN_INDEX_LOOP)!=0;

  /* If the RHS of this IN(...) operator is a SELECT, and if it matters 
  ** whether or not the SELECT result contains NULL values, check whether
  ** or not NULL is actually possible (it may not be, for example, due 
  ** to NOT NULL constraints in the schema). If no NULL values are possible,
  ** set prRhsHasNull to 0 before continuing.  */
  if( prRhsHasNull && pX->eX==EX_Select ){
    int i;
    ExprList *pEList = pX->x.pSelect->pEList;
    for(i=0; i<pEList->nExpr; i++){
      if( sqlite3ExprCanBeNull(pEList->a[i].pExpr) ) break;
    }
    if( i==pEList->nExpr ){
      prRhsHasNull = 0;

            }
          }
  
          colUsed = 0;   /* Columns of index used so far */
          for(i=0; i<nExpr; i++){
            Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
            Expr *pRhs = pEList->a[i].pExpr;
            CollSeq *pReq = sqlite3ComparisonCollSeq(pParse, pLhs, pRhs);
            int j;
  
            assert( pReq!=0 || pRhs->iColumn==XN_ROWID || pParse->nErr );
            for(j=0; j<nExpr; j++){
              if( pIdx->aiColumn[j]!=pRhs->iColumn ) continue;
              assert( pIdx->azColl[j] );
              if( pReq!=0 && sqlite3StrICmp(pReq->zName, pIdx->azColl[j])!=0 ){

  ** and IN_INDEX_NOOP is an allowed reply
  ** and the RHS of the IN operator is a list, not a subquery
  ** and the RHS is not constant or has two or fewer terms,
  ** then it is not worth creating an ephemeral table to evaluate
  ** the IN operator so return IN_INDEX_NOOP.
  */
  if( eType==0
   && (inFlags & IN_INDEX_NOOP_OK)!=0
   && pX->eX==EX_List
   && (!sqlite3InRhsIsConstant(pX) || pX->x.pList->nExpr<=2)
  ){
    eType = IN_INDEX_NOOP;
  }

  if( eType==0 ){
    /* Could not find an existing table or index to use as the RHS b-tree.
    ** We will have to generate an ephemeral table to do the job.
    */
    u32 savedNQueryLoop = pParse->nQueryLoop;
    int rMayHaveNull = 0;
    eType = IN_INDEX_EPH;
    if( inFlags & IN_INDEX_LOOP ){
      pParse->nQueryLoop = 0;
      if( pX->pLeft->iColumn<0 && pX->eX==EX_List ){
        eType = IN_INDEX_ROWID;
      }
    }else if( prRhsHasNull ){
      *prRhsHasNull = rMayHaveNull = ++pParse->nMem;
    }
    sqlite3CodeSubselect(pParse, pX, rMayHaveNull, eType==IN_INDEX_ROWID);
    pParse->nQueryLoop = savedNQueryLoop;

**
** It is the responsibility of the caller to ensure that the returned
** string is eventually freed using sqlite3DbFree().
*/
static char *exprINAffinity(Parse *pParse, Expr *pExpr){
  Expr *pLeft = pExpr->pLeft;
  int nVal = sqlite3ExprVectorSize(pLeft);
  Select *pSelect = (pExpr->eX==EX_Select) ? pExpr->x.pSelect : 0;
  char *zRet;

  assert( pExpr->op==TK_IN );
  zRet = sqlite3DbMallocRaw(pParse->db, nVal+1);
  if( zRet ){
    int i;
    for(i=0; i<nVal; i++){

**
** Or, if it is a regular scalar vector:
**
**   "row value misused"
*/   
void sqlite3VectorErrorMsg(Parse *pParse, Expr *pExpr){
#ifndef SQLITE_OMIT_SUBQUERY
  if( pExpr->eX==EX_Select ){
    sqlite3SubselectError(pParse, pExpr->x.pSelect->pEList->nExpr, 1);
  }else
#endif
  {
    sqlite3ErrorMsg(pParse, "row value misused");
  }
}

      ** is used.
      */
      pExpr->iTable = pParse->nTab++;
      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, 
          pExpr->iTable, (isRowid?0:nVal));
      pKeyInfo = isRowid ? 0 : sqlite3KeyInfoAlloc(pParse->db, nVal, 1);

      assert( pExpr->eX==EX_Select || pExpr->eX==EX_List );
      if( pExpr->eX==EX_Select ){
        /* Case 1:     expr IN (SELECT ...)
        **
        ** Generate code to write the results of the select into the temporary
        ** table allocated and opened above.
        */
        Select *pSelect = pExpr->x.pSelect;
        ExprList *pEList = pSelect->pEList;

          sqlite3DbFree(pParse->db, dest.zAffSdst);
          assert( pKeyInfo!=0 ); /* OOM will cause exit after sqlite3Select() */
          assert( pEList!=0 );
          assert( pEList->nExpr>0 );
          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
          for(i=0; i<nVal; i++){
            Expr *p = sqlite3VectorFieldSubexpr(pLeft, i);
            pKeyInfo->aColl[i] = sqlite3ComparisonCollSeq(
                pParse, p, pEList->a[i].pExpr
            );
          }
        }
      }else if( ALWAYS(pExpr->x.pList!=0) ){
        /* Case 2:     expr IN (exprlist)
        **

      SelectDest dest;                      /* How to deal with SELECT result */
      int nReg;                             /* Registers to allocate */
      Expr *pLimit;                         /* New limit expression */

      testcase( pExpr->op==TK_EXISTS );
      testcase( pExpr->op==TK_SELECT );
      assert( pExpr->op==TK_EXISTS || pExpr->op==TK_SELECT );
      assert( pExpr->eX==EX_Select );

      pSel = pExpr->x.pSelect;
      ExplainQueryPlan((pParse, 1, "%sSCALAR SUBQUERY",
            jmpIfDynamic>=0?"":"CORRELATED "));
      nReg = pExpr->op==TK_SELECT ? pSel->pEList->nExpr : 1;
      sqlite3SelectDestInit(&dest, 0, pParse->nMem+1);
      pParse->nMem += nReg;

** Expr pIn is an IN(...) expression. This function checks that the 
** sub-select on the RHS of the IN() operator has the same number of 
** columns as the vector on the LHS. Or, if the RHS of the IN() is not 
** a sub-query, that the LHS is a vector of size 1.
*/
int sqlite3ExprCheckIN(Parse *pParse, Expr *pIn){
  int nVector = sqlite3ExprVectorSize(pIn->pLeft);
  if( pIn->eX==EX_Select ){
    if( nVector!=pIn->x.pSelect->pEList->nExpr ){
      sqlite3SubselectError(pParse, pIn->x.pSelect->pEList->nExpr, nVector);
      return 1;
    }
  }else if( nVector!=1 ){
    sqlite3VectorErrorMsg(pParse, pIn->pLeft);
    return 1;

  if( eType==IN_INDEX_NOOP ){
    ExprList *pList = pExpr->x.pList;
    CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
    int labelOk = sqlite3VdbeMakeLabel(v);
    int r2, regToFree;
    int regCkNull = 0;
    int ii;
    assert( pExpr->eX==EX_List );
    if( destIfNull!=destIfFalse ){
      regCkNull = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp3(v, OP_BitAnd, rLhs, rLhs, regCkNull);
    }
    for(ii=0; ii<pList->nExpr; ii++){
      r2 = sqlite3ExprCodeTemp(pParse, pList->a[ii].pExpr, &regToFree);
      if( regCkNull && sqlite3ExprCanBeNull(pList->a[ii].pExpr) ){

      if( ExprHasProperty(pExpr, EP_FixedCol) ){
        /* This COLUMN expression is really a constant due to WHERE clause
        ** constraints, and that constant is coded by the pExpr->pLeft
        ** expresssion.  However, make sure the constant has the correct
        ** datatype by applying the Affinity of the table column to the
        ** constant.
        */
        int aff;
        int iReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft,target);
        assert( pExpr->eX==EX_Tab );
        aff = sqlite3TableColumnAffinity(pExpr->x.pTab, pExpr->iColumn);
        if( aff!=SQLITE_AFF_BLOB ){
          static const char zAff[] = "B\000C\000D\000E";
          assert( SQLITE_AFF_BLOB=='A' );
          assert( SQLITE_AFF_TEXT=='B' );
          if( iReg!=target ){
            sqlite3VdbeAddOp2(v, OP_SCopy, iReg, target);
            iReg = target;

          return pExpr->iColumn - pParse->iSelfTab;
        }else{
          /* Coding an expression that is part of an index where column names
          ** in the index refer to the table to which the index belongs */
          iTab = pParse->iSelfTab - 1;
        }
      }
      assert( pExpr->eX==EX_Tab );
      return sqlite3ExprCodeGetColumn(pParse, pExpr->x.pTab,
                               pExpr->iColumn, iTab, target,
                               pExpr->op2);
    }
    case TK_INTEGER: {
      codeInteger(pParse, pExpr, 0, target);
      return target;
    }

    case TK_NE:
    case TK_EQ: {
      Expr *pLeft = pExpr->pLeft;
      if( sqlite3ExprIsVector(pLeft) ){
        codeVectorCompare(pParse, pExpr, target, op, p5);
      }else{
        r1 = sqlite3ExprCodeTemp(pParse, pLeft, &regFree1);
        assert( pExpr->eX==EX_Right );
        r2 = sqlite3ExprCodeTemp(pParse, pExpr->x.pRight, &regFree2);
        codeCompare(pParse, pLeft, pExpr->x.pRight, op,
            r1, r2, inReg, SQLITE_STOREP2 | p5);
        assert(TK_LT==OP_Lt); testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
        assert(TK_LE==OP_Le); testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
        assert(TK_GT==OP_Gt); testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
        assert(TK_GE==OP_Ge); testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
        assert(TK_EQ==OP_Eq); testcase(op==OP_Eq); VdbeCoverageIf(v,op==OP_Eq);
        assert(TK_NE==OP_Ne); testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);

      assert( TK_BITAND==OP_BitAnd );      testcase( op==TK_BITAND );
      assert( TK_BITOR==OP_BitOr );        testcase( op==TK_BITOR );
      assert( TK_SLASH==OP_Divide );       testcase( op==TK_SLASH );
      assert( TK_LSHIFT==OP_ShiftLeft );   testcase( op==TK_LSHIFT );
      assert( TK_RSHIFT==OP_ShiftRight );  testcase( op==TK_RSHIFT );
      assert( TK_CONCAT==OP_Concat );      testcase( op==TK_CONCAT );
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      assert( pExpr->eX==EX_Right );
      r2 = sqlite3ExprCodeTemp(pParse, pExpr->x.pRight, &regFree2);
      sqlite3VdbeAddOp3(v, op, r2, r1, target);
      testcase( regFree1==0 );
      testcase( regFree2==0 );
      break;
    }
    case TK_UMINUS: {
      Expr *pLeft = pExpr->pLeft;
      assert( pLeft );
      if( pLeft->op==TK_INTEGER ){
        codeInteger(pParse, pLeft, 1, target);
        return target;
#ifndef SQLITE_OMIT_FLOATING_POINT
      }else if( pLeft->op==TK_FLOAT ){
        assert( !ExprHasProperty(pExpr, EP_IntValue) );
        codeReal(v, pLeft->u.zToken, 1, target);
        return target;
#endif
      }else{
        memset(&tempX, 0, sizeof(tempX));
        tempX.op = TK_INTEGER;
        tempX.flags = EP_IntValue|EP_TokenOnly;
        tempX.u.iValue = 0;
        r1 = sqlite3ExprCodeTemp(pParse, &tempX, &regFree1);
        r2 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree2);
        sqlite3VdbeAddOp3(v, OP_Subtract, r2, r1, target);
        testcase( regFree2==0 );

      break;
    }
    case TK_TRUTH: {
      int isTrue;    /* IS TRUE or IS NOT TRUE */
      int bNormal;   /* IS TRUE or IS FALSE */
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      testcase( regFree1==0 );
      assert( pExpr->eX==EX_Right );
      isTrue = sqlite3ExprTruthValue(pExpr->x.pRight);
      bNormal = pExpr->op2==TK_IS;
      testcase( isTrue && bNormal);
      testcase( !isTrue && bNormal);
      sqlite3VdbeAddOp4Int(v, OP_IsTrue, r1, inReg, !isTrue, isTrue ^ bNormal);
      break;
    }
    case TK_ISNULL:

#endif

      if( ConstFactorOk(pParse) && sqlite3ExprIsConstantNotJoin(pExpr) ){
        /* SQL functions can be expensive. So try to move constant functions
        ** out of the inner loop, even if that means an extra OP_Copy. */
        return sqlite3ExprCodeAtInit(pParse, pExpr, -1);
      }
      assert( pExpr->eX==EX_List || pExpr->eX==EX_None );
      if( ExprHasProperty(pExpr, EP_TokenOnly) ){
        pFarg = 0;
      }else{
        pFarg = pExpr->x.pList;
      }
      nFarg = pFarg ? pFarg->nExpr : 0;
      assert( !ExprHasProperty(pExpr, EP_IntValue) );

      **
      ** Then p1 is interpreted as follows:
      **
      **   p1==0   ->    old.rowid     p1==3   ->    new.rowid
      **   p1==1   ->    old.a         p1==4   ->    new.a
      **   p1==2   ->    old.b         p1==5   ->    new.b       
      */
      Table *pTab;
      assert( pExpr->eX==EX_Tab );
      pTab = pExpr->x.pTab;
      int p1 = pExpr->iTable * (pTab->nCol+1) + 1 + pExpr->iColumn;

      assert( pExpr->iTable==0 || pExpr->iTable==1 );
      assert( pExpr->iColumn>=-1 && pExpr->iColumn<pTab->nCol );
      assert( pTab->iPKey<0 || pExpr->iColumn!=pTab->iPKey );
      assert( p1>=0 && p1<(pTab->nCol*2+2) );

      sqlite3VdbeAddOp2(v, OP_Param, p1, target);
      assert( pExpr->eX==EX_Tab );
      VdbeComment((v, "r[%d]=%s.%s", target,
        (pExpr->iTable ? "new" : "old"),
        (pExpr->iColumn<0 ? "rowid" : pExpr->x.pTab->aCol[pExpr->iColumn].zName)
      ));

#ifndef SQLITE_OMIT_FLOATING_POINT
      /* If the column has REAL affinity, it may currently be stored as an
      ** integer. Use OP_RealAffinity to make sure it is really real.
      **
      ** EVIDENCE-OF: R-60985-57662 SQLite will convert the value back to

      int i;                            /* Loop counter */
      ExprList *pEList;                 /* List of WHEN terms */
      struct ExprList_item *aListelem;  /* Array of WHEN terms */
      Expr opCompare;                   /* The X==Ei expression */
      Expr *pX;                         /* The X expression */
      Expr *pTest = 0;                  /* X==Ei (form A) or just Ei (form B) */

      assert( pExpr->eX==EX_List );
      assert( pExpr->x.pList->nExpr > 0);
      pEList = pExpr->x.pList;
      aListelem = pEList->a;
      nExpr = pEList->nExpr;
      endLabel = sqlite3VdbeMakeLabel(v);
      if( (pX = pExpr->pLeft)!=0 ){
        tempX = *pX;
        testcase( pX->op==TK_COLUMN );

        ** So make sure that the regFree1 register is not reused for other
        ** purposes and possibly overwritten.  */
        regFree1 = 0;
      }
      for(i=0; i<nExpr-1; i=i+2){
        if( pX ){
          assert( pTest!=0 );
          opCompare.x.pRight = aListelem[i].pExpr;
          opCompare.eX = EX_Right;
        }else{
          pTest = aListelem[i].pExpr;
        }
        nextCase = sqlite3VdbeMakeLabel(v);
        testcase( pTest->op==TK_COLUMN );
        sqlite3ExprIfFalse(pParse, pTest, nextCase, SQLITE_JUMPIFNULL);
        testcase( aListelem[i+1].pExpr->op==TK_COLUMN );

  int regFree1 = 0; /* Temporary use register */


  memset(&compLeft, 0, sizeof(Expr));
  memset(&compRight, 0, sizeof(Expr));
  memset(&exprAnd, 0, sizeof(Expr));

  assert( pExpr->eX==EX_List );
  exprX = *pExpr->pLeft;
  exprAnd.op = TK_AND;
  exprAnd.pLeft = &compLeft;
  exprAnd.x.pRight = &compRight;
  exprAnd.eX = EX_Right;
  compLeft.op = TK_GE;
  compLeft.pLeft = &exprX;
  compLeft.x.pRight = pExpr->x.pList->a[0].pExpr;
  compLeft.eX = EX_Right;
  compRight.op = TK_LE;
  compRight.pLeft = &exprX;
  compRight.x.pRight = pExpr->x.pList->a[1].pExpr;
  compRight.eX = EX_Right;
  exprToRegister(&exprX, exprCodeVector(pParse, &exprX, &regFree1));
  if( xJump ){
    xJump(pParse, &exprAnd, dest, jumpIfNull);
  }else{
    /* Mark the expression is being from the ON or USING clause of a join
    ** so that the sqlite3ExprCodeTarget() routine will not attempt to move
    ** it into the Parse.pConstExpr list.  We should use a new bit for this,

  if( NEVER(pExpr==0) ) return;  /* No way this can happen */
  op = pExpr->op;
  switch( op ){
    case TK_AND: {
      int d2 = sqlite3VdbeMakeLabel(v);
      testcase( jumpIfNull==0 );
      sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
      assert( pExpr->eX==EX_Right );
      sqlite3ExprIfTrue(pParse, pExpr->x.pRight, dest, jumpIfNull);
      sqlite3VdbeResolveLabel(v, d2);
      break;
    }
    case TK_OR: {
      testcase( jumpIfNull==0 );
      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
      assert( pExpr->eX==EX_Right );
      sqlite3ExprIfTrue(pParse, pExpr->x.pRight, dest, jumpIfNull);
      break;
    }
    case TK_NOT: {
      testcase( jumpIfNull==0 );
      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
      break;
    }
    case TK_TRUTH: {
      int isNot;      /* IS NOT TRUE or IS NOT FALSE */
      int isTrue;     /* IS TRUE or IS NOT TRUE */
      testcase( jumpIfNull==0 );
      isNot = pExpr->op2==TK_ISNOT;
      assert( pExpr->eX==EX_Right );
      isTrue = sqlite3ExprTruthValue(pExpr->x.pRight);
      testcase( isTrue && isNot );
      testcase( !isTrue && isNot );
      if( isTrue ^ isNot ){
        sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest,
                          isNot ? SQLITE_JUMPIFNULL : 0);
      }else{
        sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest,

    case TK_GT:
    case TK_GE:
    case TK_NE:
    case TK_EQ: {
      if( sqlite3ExprIsVector(pExpr->pLeft) ) goto default_expr;
      testcase( jumpIfNull==0 );
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      assert( pExpr->eX==EX_Right );
      r2 = sqlite3ExprCodeTemp(pParse, pExpr->x.pRight, &regFree2);
      codeCompare(pParse, pExpr->pLeft, pExpr->x.pRight, op,
                  r1, r2, dest, jumpIfNull);
      assert(TK_LT==OP_Lt); testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
      assert(TK_LE==OP_Le); testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
      assert(TK_GT==OP_Gt); testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
      assert(TK_GE==OP_Ge); testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
      assert(TK_EQ==OP_Eq); testcase(op==OP_Eq);
      VdbeCoverageIf(v, op==OP_Eq && jumpIfNull==SQLITE_NULLEQ);

  assert( pExpr->op!=TK_GT || op==OP_Le );
  assert( pExpr->op!=TK_GE || op==OP_Lt );

  switch( pExpr->op ){
    case TK_AND: {
      testcase( jumpIfNull==0 );
      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
      assert( pExpr->eX==EX_Right );
      sqlite3ExprIfFalse(pParse, pExpr->x.pRight, dest, jumpIfNull);
      break;
    }
    case TK_OR: {
      int d2 = sqlite3VdbeMakeLabel(v);
      testcase( jumpIfNull==0 );
      sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
      assert( pExpr->eX==EX_Right );
      sqlite3ExprIfFalse(pParse, pExpr->x.pRight, dest, jumpIfNull);
      sqlite3VdbeResolveLabel(v, d2);
      break;
    }
    case TK_NOT: {
      testcase( jumpIfNull==0 );
      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
      break;
    }
    case TK_TRUTH: {
      int isNot;   /* IS NOT TRUE or IS NOT FALSE */
      int isTrue;  /* IS TRUE or IS NOT TRUE */
      testcase( jumpIfNull==0 );
      isNot = pExpr->op2==TK_ISNOT;
      assert( pExpr->eX==EX_Right );
      isTrue = sqlite3ExprTruthValue(pExpr->x.pRight);
      testcase( isTrue && isNot );
      testcase( !isTrue && isNot );
      if( isTrue ^ isNot ){
        /* IS TRUE and IS NOT FALSE */
        sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest,
                           isNot ? 0 : SQLITE_JUMPIFNULL);

    case TK_GT:
    case TK_GE:
    case TK_NE:
    case TK_EQ: {
      if( sqlite3ExprIsVector(pExpr->pLeft) ) goto default_expr;
      testcase( jumpIfNull==0 );
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      assert( pExpr->eX==EX_Right );
      r2 = sqlite3ExprCodeTemp(pParse, pExpr->x.pRight, &regFree2);
      codeCompare(pParse, pExpr->pLeft, pExpr->x.pRight, op,
                  r1, r2, dest, jumpIfNull);
      assert(TK_LT==OP_Lt); testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
      assert(TK_LE==OP_Le); testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
      assert(TK_GT==OP_Gt); testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
      assert(TK_GE==OP_Ge); testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
      assert(TK_EQ==OP_Eq); testcase(op==OP_Eq);
      VdbeCoverageIf(v, op==OP_Eq && jumpIfNull!=SQLITE_NULLEQ);

      if( sqlite3_stricmp(pA->u.zToken,pB->u.zToken)!=0 ) return 2;
    }else if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
      return 2;
    }
  }
  if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 2;
  if( ALWAYS((combinedFlags & EP_TokenOnly)==0) ){
    if( pA->eX==EX_Select || pA->eX!=pB->eX ) return 2;
    if( (combinedFlags & EP_FixedCol)==0
     && sqlite3ExprCompare(pParse, pA->pLeft, pB->pLeft, iTab) ) return 2;
    if( pA->eX==EX_Right ){
      if( sqlite3ExprCompare(pParse,pA->x.pRight,pB->x.pRight,iTab) ) return 2;
    }
    if( pA->eX==EX_List ){
      if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList, iTab) ) return 2;
    }
    assert( (combinedFlags & EP_Reduced)==0 );
    if( pA->op!=TK_STRING && pA->op!=TK_TRUEFALSE ){
      if( pA->iColumn!=pB->iColumn ) return 2;
      if( pA->iTable!=pB->iTable 
       && (pA->iTable!=iTab || NEVER(pB->iTable>=0)) ) return 2;
    }
#ifndef SQLITE_OMIT_WINDOWFUNC

** improvement.  Returning false might cause a performance reduction, but
** it will always give the correct answer and is hence always safe.
*/
int sqlite3ExprImpliesExpr(Parse *pParse, Expr *pE1, Expr *pE2, int iTab){
  if( sqlite3ExprCompare(pParse, pE1, pE2, iTab)==0 ){
    return 1;
  }
  assert( pE2->op!=TK_OR || pE2->eX==EX_Right );
  if( pE2->op==TK_OR
   && (sqlite3ExprImpliesExpr(pParse, pE1, pE2->pLeft, iTab)
             || sqlite3ExprImpliesExpr(pParse, pE1, pE2->x.pRight, iTab) )
  ){
    return 1;
  }
  if( pE2->op==TK_NOTNULL && pE1->op!=TK_ISNULL && pE1->op!=TK_IS ){
    Expr *pX = sqlite3ExprSkipCollate(pE1->pLeft);
    testcase( pX!=pE1->pLeft );
    if( sqlite3ExprCompare(pParse, pX, pE2->pLeft, iTab)==0 ) return 1;

    case TK_GE:
      testcase( pExpr->op==TK_EQ );
      testcase( pExpr->op==TK_NE );
      testcase( pExpr->op==TK_LT );
      testcase( pExpr->op==TK_LE );
      testcase( pExpr->op==TK_GT );
      testcase( pExpr->op==TK_GE );
      assert( pExpr->eX==EX_Right );
      if( (pExpr->pLeft->op==TK_COLUMN && IsVirtual(pExpr->pLeft->x.pTab))
       || (pExpr->x.pRight->op==TK_COLUMN && IsVirtual(pExpr->x.pRight->x.pTab))
      ){
       return WRC_Prune;
      }
    default:
      return WRC_Continue;
  }
}

                break;
              }
            }
            if( (k>=pAggInfo->nColumn)
             && (k = addAggInfoColumn(pParse->db, pAggInfo))>=0 
            ){
              pCol = &pAggInfo->aCol[k];
              assert( pExpr->eX==EX_Tab );
              pCol->pTab = pExpr->x.pTab;
              pCol->iTable = pExpr->iTable;
              pCol->iColumn = pExpr->iColumn;
              pCol->iMem = ++pParse->nMem;
              pCol->iSorterColumn = -1;
              pCol->pExpr = pExpr;
              if( pAggInfo->pGroupBy ){
                int j, n;

        }
        if( i>=pAggInfo->nFunc ){
          /* pExpr is original.  Make a new entry in pAggInfo->aFunc[]
          */
          u8 enc = ENC(pParse->db);
          i = addAggInfoFunc(pParse->db, pAggInfo);
          if( i>=0 ){
            assert( pExpr->eX==EX_List || pExpr->eX==EX_None );
            pItem = &pAggInfo->aFunc[i];
            pItem->pExpr = pExpr;
            pItem->iMem = ++pParse->nMem;
            assert( !ExprHasProperty(pExpr, EP_IntValue) );
            pItem->pFunc = sqlite3FindFunction(pParse->db,
                   pExpr->u.zToken, 
                   pExpr->eX==EX_List ? pExpr->x.pList->nExpr : 0, enc, 0);
            if( pExpr->flags & EP_Distinct ){
              pItem->iDistinct = pParse->nTab++;
            }else{
              pItem->iDistinct = -1;
            }
          }
        }

  sqlite3 *db,      /* The database connection */
  Table *pTab,      /* The table whose column is desired */
  int iCursor,      /* The open cursor on the table */
  i16 iCol          /* The column that is wanted */
){
  Expr *pExpr = sqlite3Expr(db, TK_COLUMN, 0);
  if( pExpr ){
    assert( pExpr->eX==EX_None );
    if( pTab ){
      pExpr->x.pTab = pTab;
      pExpr->eX = EX_Tab;
    }
    pExpr->iTable = iCursor;
    pExpr->iColumn = iCol;
  }
  return pExpr;
}

/*

*/
int sqlite3IsLikeFunction(sqlite3 *db, Expr *pExpr, int *pIsNocase, char *aWc){
  FuncDef *pDef;
  int nExpr;
  if( pExpr->op!=TK_FUNCTION || !pExpr->x.pList ){
    return 0;
  }
  assert( pExpr->eX==EX_List );
  nExpr = pExpr->x.pList->nExpr;
  pDef = sqlite3FindFunction(db, pExpr->u.zToken, nExpr, SQLITE_UTF8, 0);
  if( NEVER(pDef==0) || (pDef->funcFlags & SQLITE_FUNC_LIKE)==0 ){
    return 0;
  }
  if( nExpr<3 ){
    aWc[3] = 0;

  */
  static Expr *tokenExpr(Parse *pParse, int op, Token t){
    Expr *p = sqlite3DbMallocRawNN(pParse->db, sizeof(Expr)+t.n+1);
    if( p ){
      /* memset(p, 0, sizeof(Expr)); */
      p->op = (u8)op;
      p->affinity = 0;
      p->eX = EX_None;
      p->flags = EP_Leaf;
      p->iAgg = -1;
      p->pLeft = 0;

      p->pAggInfo = 0;

      p->op2 = 0;
      p->iTable = 0;
      p->iColumn = 0;
#ifndef SQLITE_OMIT_WINDOWFUNC
      p->pWin = 0;
#endif
      p->u.zToken = (char*)&p[1];

term(A) ::= CTIME_KW(OP). {
  A = sqlite3ExprFunction(pParse, 0, &OP, 0);
}

expr(A) ::= LP nexprlist(X) COMMA expr(Y) RP. {
  ExprList *pList = sqlite3ExprListAppend(pParse, X, Y);
  A = sqlite3PExpr(pParse, TK_VECTOR, 0, 0);



  sqlite3PExprAddExprList(pParse, A, pList);

}

expr(A) ::= expr(A) AND(OP) expr(Y).    {A=sqlite3PExpr(pParse,@OP,A,Y);}
expr(A) ::= expr(A) OR(OP) expr(Y).     {A=sqlite3PExpr(pParse,@OP,A,Y);}
expr(A) ::= expr(A) LT|GT|GE|LE(OP) expr(Y).
                                        {A=sqlite3PExpr(pParse,@OP,A,Y);}
expr(A) ::= expr(A) EQ|NE(OP) expr(Y).  {A=sqlite3PExpr(pParse,@OP,A,Y);}

expr(A) ::= expr(A) NOT NULL.    {A = sqlite3PExpr(pParse,TK_NOTNULL,A,0);}

%include {
  /* A routine to convert a binary TK_IS or TK_ISNOT expression into a
  ** unary TK_ISNULL or TK_NOTNULL expression. */
  static void binaryToUnaryIfNull(Parse *pParse, Expr *pY, Expr *pA, int op){
    sqlite3 *db = pParse->db;
    if( pA && pY && pY->op==TK_NULL && pA->eX==EX_Right && !IN_RENAME_OBJECT ){
      pA->op = (u8)op;
      sqlite3ExprDelete(db, pA->x.pRight);
      pA->x.pRight = 0;
      pA->eX = EX_None;
    }
  }
}

//    expr1 IS expr2
//    expr1 IS NOT expr2
//

%type between_op {int}
between_op(A) ::= BETWEEN.     {A = 0;}
between_op(A) ::= NOT BETWEEN. {A = 1;}
expr(A) ::= expr(A) between_op(N) expr(X) AND expr(Y). [BETWEEN] {
  ExprList *pList = sqlite3ExprListAppend(pParse,0, X);
  pList = sqlite3ExprListAppend(pParse,pList, Y);
  A = sqlite3PExpr(pParse, TK_BETWEEN, A, 0);



  sqlite3PExprAddExprList(pParse, A, pList);

  if( N ) A = sqlite3PExpr(pParse, TK_NOT, A, 0);
}
%ifndef SQLITE_OMIT_SUBQUERY
  %type in_op {int}
  in_op(A) ::= IN.      {A = 0;}
  in_op(A) ::= NOT IN.  {A = 1;}
  expr(A) ::= expr(A) in_op(N) LP exprlist(Y) RP. [IN] {

      if( ALWAYS(pRHS) ){
        pRHS->flags &= ~EP_Collate;
        pRHS->flags |= EP_Generic;
      }
      A = sqlite3PExpr(pParse, N ? TK_NE : TK_EQ, A, pRHS);
    }else{
      A = sqlite3PExpr(pParse, TK_IN, A, 0);

      sqlite3PExprAddExprList(pParse, A, Y);
      sqlite3ExprSetHeightAndFlags(pParse, A);



      if( N ) A = sqlite3PExpr(pParse, TK_NOT, A, 0);
    }
  }
  expr(A) ::= LP select(X) RP. {
    A = sqlite3PExpr(pParse, TK_SELECT, 0, 0);
    sqlite3PExprAddSelect(pParse, A, X);
  }

    sqlite3PExprAddSelect(pParse, p, Y);
  }
%endif SQLITE_OMIT_SUBQUERY

/* CASE expressions */
expr(A) ::= CASE case_operand(X) case_exprlist(Y) case_else(Z) END. {
  A = sqlite3PExpr(pParse, TK_CASE, X, 0);

  sqlite3PExprAddExprList(pParse,A,Z ? sqlite3ExprListAppend(pParse,Y,Z) : Y);
  sqlite3ExprSetHeightAndFlags(pParse, A);




}
%type case_exprlist {ExprList*}
%destructor case_exprlist {sqlite3ExprListDelete(pParse->db, $$);}
case_exprlist(A) ::= case_exprlist(A) WHEN expr(Y) THEN expr(Z). {
  A = sqlite3ExprListAppend(pParse,A, Y);
  A = sqlite3ExprListAppend(pParse,A, Z);
}

**    pExpr->iTable        Set to the cursor number for the table obtained
**                         from pSrcList.
**    pExpr->pTab          Points to the Table structure of X.Y (even if
**                         X and/or Y are implied.)
**    pExpr->iColumn       Set to the column number within the table.
**    pExpr->op            Set to TK_COLUMN.
**    pExpr->pLeft         Any expression this points to is deleted
**    pExpr->x.pRight      Any expression this points to is deleted.
**
** The zDb variable is the name of the database (the "X").  This value may be
** NULL meaning that name is of the form Y.Z or Z.  Any available database
** can be used.  The zTable variable is the name of the table (the "Y").  This
** value can be NULL if zDb is also NULL.  If zTable is NULL it
** means that the form of the name is Z and that columns from any table
** can be used.

  assert( pNC );     /* the name context cannot be NULL. */
  assert( zCol );    /* The Z in X.Y.Z cannot be NULL */
  assert( !ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced) );

  /* Initialize the node to no-match */
  pExpr->iTable = -1;

  ExprSetVVAProperty(pExpr, EP_NoReduce);

  /* Translate the schema name in zDb into a pointer to the corresponding
  ** schema.  If not found, pSchema will remain NULL and nothing will match
  ** resulting in an appropriate error message toward the end of this routine
  */
  if( zDb ){

        if( zTab ){
          const char *zTabName = pItem->zAlias ? pItem->zAlias : pTab->zName;
          assert( zTabName!=0 );
          if( sqlite3StrICmp(zTabName, zTab)!=0 ){
            continue;
          }
          if( IN_RENAME_OBJECT && pItem->zAlias ){
            sqlite3RenameTokenRemap(pParse, 0, (void*)&pExpr->x.pTab);
          }
        }
        if( 0==(cntTab++) ){
          pMatch = pItem;
        }
        for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
          if( sqlite3StrICmp(pCol->zName, zCol)==0 ){

            pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;
            break;
          }
        }
      }
      if( pMatch ){
        pExpr->iTable = pMatch->iCursor;
        sqlite3ExprAddTab(db, pExpr, pMatch->pTab);
        /* RIGHT JOIN not (yet) supported */
        assert( (pMatch->fg.jointype & JT_RIGHT)==0 );
        if( (pMatch->fg.jointype & JT_LEFT)!=0 ){
          ExprSetProperty(pExpr, EP_CanBeNull);
        }
        pSchema = pExpr->x.pTab->pSchema;
      }
    } /* if( pSrcList ) */

#if !defined(SQLITE_OMIT_TRIGGER) || !defined(SQLITE_OMIT_UPSERT)
    /* If we have not already resolved the name, then maybe 
    ** it is a new.* or old.* trigger argument reference.  Or
    ** maybe it is an excluded.* from an upsert.

        if( iCol<pTab->nCol ){
          cnt++;
#ifndef SQLITE_OMIT_UPSERT
          if( pExpr->iTable==2 ){
            testcase( iCol==(-1) );
            if( IN_RENAME_OBJECT ){
              pExpr->iColumn = iCol;
              sqlite3ExprAddTab(db, pExpr, pTab);
              eNewExprOp = TK_COLUMN;
            }else{
              pExpr->iTable = pNC->uNC.pUpsert->regData + iCol;
              eNewExprOp = TK_REGISTER;
              ExprSetProperty(pExpr, EP_Alias);
            }
          }else

              testcase( iCol==32 );
              pParse->oldmask |= (iCol>=32 ? 0xffffffff : (((u32)1)<<iCol));
            }else{
              testcase( iCol==31 );
              testcase( iCol==32 );
              pParse->newmask |= (iCol>=32 ? 0xffffffff : (((u32)1)<<iCol));
            }
            sqlite3ExprAddTab(db, pExpr, pTab);
            pExpr->iColumn = (i16)iCol;
            eNewExprOp = TK_TRIGGER;
#endif /* SQLITE_OMIT_TRIGGER */
          }
        }
      }
    }

    ){
      pEList = pNC->uNC.pEList;
      assert( pEList!=0 );
      for(j=0; j<pEList->nExpr; j++){
        char *zAs = pEList->a[j].zName;
        if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
          Expr *pOrig;
          assert( pExpr->pLeft==0 );


          pOrig = pEList->a[j].pExpr;
          if( (pNC->ncFlags&NC_AllowAgg)==0 && ExprHasProperty(pOrig, EP_Agg) ){
            sqlite3ErrorMsg(pParse, "misuse of aliased aggregate %s", zAs);
            return WRC_Abort;
          }
          if( sqlite3ExprVectorSize(pOrig)!=1 ){
            sqlite3ErrorMsg(pParse, "row value misused");

  ** Because no reference was made to outer contexts, the pNC->nRef
  ** fields are not changed in any context.
  */
  if( cnt==0 && zTab==0 ){
    assert( pExpr->op==TK_ID );
    if( ExprHasProperty(pExpr,EP_DblQuoted) ){
      pExpr->op = TK_STRING;

      return WRC_Prune;
    }
    if( sqlite3ExprIdToTrueFalse(pExpr) ){
      return WRC_Prune;
    }
  }

    pMatch->colUsed |= ((Bitmask)1)<<n;
  }

  /* Clean up and return
  */
  sqlite3ExprDelete(db, pExpr->pLeft);
  pExpr->pLeft = 0;
  if( pExpr->eX==EX_Right ){
    sqlite3ExprDelete(db, pExpr->x.pRight);
    pExpr->x.pRight = 0;
    pExpr->eX = EX_None;
  }
  pExpr->op = eNewExprOp;
  ExprSetProperty(pExpr, EP_Leaf);
lookupname_end:
  if( cnt==1 ){
    assert( pNC!=0 );
    if( !ExprHasProperty(pExpr, EP_Alias) ){
      sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);

** Allocate and return a pointer to an expression to load the column iCol
** from datasource iSrc in SrcList pSrc.
*/
Expr *sqlite3CreateColumnExpr(sqlite3 *db, SrcList *pSrc, int iSrc, int iCol){
  Expr *p = sqlite3ExprAlloc(db, TK_COLUMN, 0, 0);
  if( p ){
    struct SrcList_item *pItem = &pSrc->a[iSrc];
    sqlite3ExprAddTab(db, p, pItem->pTab);
    p->iTable = pItem->iCursor;
    if( p->x.pTab->iPKey==iCol ){
      p->iColumn = -1;
    }else{
      p->iColumn = (ynVar)iCol;
      testcase( iCol==BMS );
      testcase( iCol==BMS-1 );
      pItem->colUsed |= ((Bitmask)1)<<(iCol>=BMS ? BMS-1 : iCol);
    }

      if( pExpr->op==TK_ID ){
        zDb = 0;
        zTable = 0;
        zColumn = pExpr->u.zToken;
      }else{
        Expr *pLeft = pExpr->pLeft;
        notValid(pParse, pNC, "the \".\" operator", NC_IdxExpr);
        assert( pExpr->eX==EX_Right );
        pRight = pExpr->x.pRight;
        if( pRight->op==TK_ID ){
          zDb = 0;
        }else{
          assert( pRight->op==TK_DOT );
          assert( pRight->eX==EX_Right );
          zDb = pLeft->u.zToken;
          pLeft = pRight->pLeft;
          pRight = pRight->x.pRight;
        }
        zTable = pLeft->u.zToken;
        zColumn = pRight->u.zToken;
        if( IN_RENAME_OBJECT ){
          sqlite3RenameTokenRemap(pParse, (void*)pExpr, (void*)pRight);

          if( pExpr->eX==EX_Tab ){
            sqlite3RenameTokenRemap(pParse, (void*)&pExpr->x.pTab,(void*)pLeft);
          }
        }
      }
      return lookupName(pParse, zDb, zTable, zColumn, pNC, pExpr);
    }

    /* Resolve function names
    */
    case TK_FUNCTION: {
      ExprList *pList;            /* The argument list */
      int n;                      /* Number of arguments */
      int no_such_func = 0;       /* True if no such function exists */
      int wrong_num_args = 0;     /* True if wrong number of arguments */
      int is_agg = 0;             /* True if is an aggregate function */
      int nId;                    /* Number of characters in function name */
      const char *zId;            /* The function name. */
      FuncDef *pDef;              /* Information about the function */
      u8 enc = ENC(pParse->db);   /* The database encoding */

      assert( pExpr->eX==EX_List || pExpr->eX==EX_None );
      if( pExpr->eX==EX_List ){
        pList = pExpr->x.pList;
        n = pList->nExpr;
      }else{
        pList = 0;
        n = 0;
      }
      zId = pExpr->u.zToken;
      nId = sqlite3Strlen30(zId);
      pDef = sqlite3FindFunction(pParse->db, zId, n, enc, 0);
      if( pDef==0 ){
        pDef = sqlite3FindFunction(pParse->db, zId, -2, enc, 0);
        if( pDef==0 ){
          no_such_func = 1;

    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_SELECT:
    case TK_EXISTS:  testcase( pExpr->op==TK_EXISTS );
#endif
    case TK_IN: {
      testcase( pExpr->op==TK_IN );
      if( pExpr->eX==EX_Select ){
        int nRef = pNC->nRef;
        notValid(pParse, pNC, "subqueries", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
        sqlite3WalkSelect(pWalker, pExpr->x.pSelect);
        assert( pNC->nRef>=nRef );
        if( nRef!=pNC->nRef ){
          ExprSetProperty(pExpr, EP_VarSelect);
          pNC->ncFlags |= NC_VarSelect;

    }
    case TK_IS:
    case TK_ISNOT: {
      Expr *pRight;
      assert( !ExprHasProperty(pExpr, EP_Reduced) );
      /* Handle special cases of "x IS TRUE", "x IS FALSE", "x IS NOT TRUE",
      ** and "x IS NOT FALSE". */
      assert( pExpr->eX==EX_Right );
      if( (pRight = pExpr->x.pRight)->op==TK_ID ){
        int rc = resolveExprStep(pWalker, pRight);
        if( rc==WRC_Abort ) return WRC_Abort;
        if( pRight->op==TK_TRUEFALSE ){
          pExpr->op2 = pExpr->op;
          pExpr->op = TK_TRUTH;
          return WRC_Continue;
        }

      nLeft = sqlite3ExprVectorSize(pExpr->pLeft);
      if( pExpr->op==TK_BETWEEN ){
        nRight = sqlite3ExprVectorSize(pExpr->x.pList->a[0].pExpr);
        if( nRight==nLeft ){
          nRight = sqlite3ExprVectorSize(pExpr->x.pList->a[1].pExpr);
        }
      }else{
        assert( pExpr->eX==EX_Right );
        nRight = sqlite3ExprVectorSize(pExpr->x.pRight);
      }
      if( nLeft!=nRight ){
        testcase( pExpr->op==TK_EQ );
        testcase( pExpr->op==TK_NE );
        testcase( pExpr->op==TK_LT );
        testcase( pExpr->op==TK_LE );
        testcase( pExpr->op==TK_GT );

*/
static void setJoinExpr(Expr *p, int iTable){
  while( p ){
    ExprSetProperty(p, EP_FromJoin);
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    ExprSetVVAProperty(p, EP_NoReduce);
    p->iRightJoinTable = (i16)iTable;
    if( p->op==TK_FUNCTION && p->eX==EX_List ){
      int i;
      for(i=0; i<p->x.pList->nExpr; i++){
        setJoinExpr(p->x.pList->a[i].pExpr, iTable);
      }
    }
    setJoinExpr(p->pLeft, iTable);
    p = p->eX==EX_Right ? p->x.pRight : 0;
  } 
}

/* Undo the work of setJoinExpr().  In the expression tree p, convert every
** term that is marked with EP_FromJoin and iRightJoinTable==iTable into
** an ordinary term that omits the EP_FromJoin mark.
**
** This happens when a LEFT JOIN is simplified into an ordinary JOIN.
*/
static void unsetJoinExpr(Expr *p, int iTable){
  while( p ){
    if( ExprHasProperty(p, EP_FromJoin)
     && (iTable<0 || p->iRightJoinTable==iTable) ){
      ExprClearProperty(p, EP_FromJoin);
    }
    if( p->op==TK_FUNCTION && p->eX==EX_List ){
      int i;
      for(i=0; i<p->x.pList->nExpr; i++){
        unsetJoinExpr(p->x.pList->a[i].pExpr, iTable);
      }
    }
    unsetJoinExpr(p->pLeft, iTable);
    p = p->eX==EX_Right ? p->x.pRight : 0;
  } 
}

/*
** This routine processes the join information for a SELECT statement.
** ON and USING clauses are converted into extra terms of the WHERE clause.
** NATURAL joins also create extra WHERE clause terms.

  int i;
  int nDefer = 0;
  ExprList *pExtra = 0;
  for(i=0; i<pEList->nExpr; i++){
    struct ExprList_item *pItem = &pEList->a[i];
    if( pItem->u.x.iOrderByCol==0 ){
      Expr *pExpr = pItem->pExpr;
      Table *pTab;
      if( pExpr->op==TK_COLUMN
       && pExpr->iColumn>=0
       && ALWAYS(pExpr->eX==EX_Tab)
       && (pTab = pExpr->x.pTab)!=0
       && !IsVirtual(pTab)
       && (pTab->aCol[pExpr->iColumn].colFlags & COLFLAG_SORTERREF)
      ){
        int j;
        for(j=0; j<nDefer; j++){
          if( pSort->aDefer[j].iCsr==pExpr->iTable ) break;
        }
        if( j==nDefer ){
          if( nDefer==ArraySize(pSort->aDefer) ){
            continue;
          }else{
            int nKey = 1;
            int k;
            Index *pPk = 0;
            if( !HasRowid(pTab) ){
              pPk = sqlite3PrimaryKeyIndex(pTab);
              nKey = pPk->nKeyCol;
            }
            assert( pExpr->eX==EX_Tab );
            for(k=0; k<nKey; k++){
              Expr *pNew = sqlite3PExpr(pParse, TK_COLUMN, 0, 0);
              if( pNew ){
                pNew->iTable = pExpr->iTable;
                pNew->eX = EX_Tab;
                pNew->x.pTab = pExpr->x.pTab;
                pNew->iColumn = pPk ? pPk->aiColumn[k] : -1;
                pExtra = sqlite3ExprListAppend(pParse, pExtra, pNew);
              }
            }
            pSort->aDefer[nDefer].pTab = pExpr->x.pTab;
            pSort->aDefer[nDefer].iCsr = pExpr->iTable;
            pSort->aDefer[nDefer].nKey = nKey;
            nDefer++;
          }
        }
        pItem->bSorterRef = 1;
      }

        ** This is not a problem, as the column type of "t1.col" is never
        ** used. When columnType() is called on the expression 
        ** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT
        ** branch below.  */
        break;
      }

      assert( pTab && pExpr->eX==EX_Tab && pExpr->x.pTab==pTab );
      if( pS ){
        /* The "table" is actually a sub-select or a view in the FROM clause
        ** of the SELECT statement. Return the declaration type and origin
        ** data for the result-set column of the sub-select.
        */
        if( iCol>=0 && iCol<pS->pEList->nExpr ){
          /* If iCol is less than zero, then the expression requests the

      /* The expression is a sub-select. Return the declaration type and
      ** origin info for the single column in the result set of the SELECT
      ** statement.
      */
      NameContext sNC;
      Select *pS = pExpr->x.pSelect;
      Expr *p = pS->pEList->a[0].pExpr;
      assert( pExpr->eX==EX_Select );
      sNC.pSrcList = pS->pSrc;
      sNC.pNext = pNC;
      sNC.pParse = pNC->pParse;
      zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol); 
      break;
    }
#endif

  srcName = (db->flags & SQLITE_ShortColNames)!=0 || fullName;
  sqlite3VdbeSetNumCols(v, pEList->nExpr);
  for(i=0; i<pEList->nExpr; i++){
    Expr *p = pEList->a[i].pExpr;

    assert( p!=0 );
    assert( p->op!=TK_AGG_COLUMN );  /* Agg processing has not run yet */
    /* Covering idx not yet coded: */
    assert( p->op!=TK_COLUMN || (p->eX==EX_Tab && p->x.pTab!=0) );
    if( pEList->a[i].zName ){
      /* An AS clause always takes first priority */
      char *zName = pEList->a[i].zName;
      sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT);
    }else if( srcName && p->op==TK_COLUMN ){
      char *zCol;
      int iCol = p->iColumn;
      assert( p->eX==EX_Tab );
      pTab = p->x.pTab;
      assert( pTab!=0 );
      if( iCol<0 ) iCol = pTab->iPKey;
      assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
      if( iCol<0 ){
        zCol = "rowid";
      }else{
        zCol = pTab->aCol[iCol].zName;

    /* Get an appropriate name for the column
    */
    if( (zName = pEList->a[i].zName)!=0 ){
      /* If the column contains an "AS <name>" phrase, use <name> as the name */
    }else{
      Expr *pColExpr = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
      while( pColExpr->op==TK_DOT ){
        assert( pColExpr->eX==EX_Right );
        pColExpr = pColExpr->x.pRight;
        assert( pColExpr!=0 );
      }
      assert( pColExpr->op!=TK_AGG_COLUMN );
      if( pColExpr->op==TK_COLUMN ){
        /* For columns use the column name name */
        int iCol = pColExpr->iColumn;
        Table *pTab;
        assert( pColExpr->eX==EX_Tab );
        pTab = pColExpr->x.pTab;
        assert( pTab!=0 );
        if( iCol<0 ) iCol = pTab->iPKey;
        zName = iCol>=0 ? pTab->aCol[iCol].zName : "rowid";
      }else if( pColExpr->op==TK_ID ){
        assert( !ExprHasProperty(pColExpr, EP_IntValue) );
        zName = pColExpr->u.zToken;
      }else{

  }
  return sqlite3VdbeCreate(pParse);
}


/*
** Compute the iLimit and iOffset fields of the SELECT based on the
** pLimit expressions.  pLimit->pLeft and pLimit->x,pRight hold the expressions
** that appear in the original SQL statement after the LIMIT and OFFSET
** keywords.  Or NULL if those keywords are omitted. iLimit and iOffset 
** are the integer memory register numbers for counters used to compute 
** the limit and offset.  If there is no limit and/or offset, then 
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit->pLeft and pLimit->x.pRight.  iLimit
** and iOffset should have been preset to appropriate default values (zero)
** prior to calling this routine.
**
** The iOffset register (if it exists) is initialized to the value
** of the OFFSET.  The iLimit register is initialized to LIMIT.  Register
** iOffset+1 is initialized to LIMIT+OFFSET.
**

      }
    }else{
      sqlite3ExprCode(pParse, pLimit->pLeft, iLimit);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v);
      VdbeComment((v, "LIMIT counter"));
      sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v);
    }
    if( pLimit->eX==EX_Right ){
      p->iOffset = iOffset = ++pParse->nMem;
      pParse->nMem++;   /* Allocate an extra register for limit+offset */
      sqlite3ExprCode(pParse, pLimit->x.pRight, iOffset);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v);
      VdbeComment((v, "OFFSET counter"));
      sqlite3VdbeAddOp3(v, OP_OffsetLimit, iLimit, iOffset+1, iOffset);
      VdbeComment((v, "LIMIT+OFFSET"));
    }
  }
}

    if( pExpr->iColumn<0 ){
      pExpr->op = TK_NULL;
    }else{
      Expr *pNew;
      Expr *pCopy = pSubst->pEList->a[pExpr->iColumn].pExpr;
      Expr ifNullRow;
      assert( pSubst->pEList!=0 && pExpr->iColumn<pSubst->pEList->nExpr );
      assert( pExpr->eX!=EX_Right );
      if( sqlite3ExprIsVector(pCopy) ){
        sqlite3VectorErrorMsg(pSubst->pParse, pCopy);
      }else{
        sqlite3 *db = pSubst->pParse->db;
        if( pSubst->isLeftJoin && pCopy->op!=TK_COLUMN ){
          memset(&ifNullRow, 0, sizeof(ifNullRow));
          ifNullRow.op = TK_IF_NULL_ROW;

      }
    }
  }else{
    if( pExpr->op==TK_IF_NULL_ROW && pExpr->iTable==pSubst->iTable ){
      pExpr->iTable = pSubst->iNewTable;
    }
    pExpr->pLeft = substExpr(pSubst, pExpr->pLeft);
    switch( pExpr->eX ){
      case EX_Select: {
        substSelect(pSubst, pExpr->x.pSelect, 1);
        break;
      }
      case EX_List: {
        substExprList(pSubst, pExpr->x.pList);
        break;
      }
      case EX_Right: {
        pExpr->x.pRight = substExpr(pSubst, pExpr->x.pRight);
        if( pExpr->x.pRight==0 ) pExpr->eX = EX_None;
        break;
      }
    }
  }
  return pExpr;
}
static void substExprList(
  SubstContext *pSubst, /* Description of the substitution */
  ExprList *pList       /* List to scan and in which to make substitutes */

  assert( pSubSrc );
  /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
  ** not arbitrary expressions, we allowed some combining of LIMIT and OFFSET
  ** because they could be computed at compile-time.  But when LIMIT and OFFSET
  ** became arbitrary expressions, we were forced to add restrictions (13)
  ** and (14). */
  if( pSub->pLimit && p->pLimit ) return 0;              /* Restriction (13) */
  if( pSub->pLimit && pSub->pLimit->eX==EX_Right ){
    return 0;                                            /* Restriction (14) */
  }
  if( (p->selFlags & SF_Compound)!=0 && pSub->pLimit ){
    return 0;                                            /* Restriction (15) */
  }
  if( pSubSrc->nSrc==0 ) return 0;                       /* Restriction (7)  */
  if( pSub->selFlags & SF_Distinct ) return 0;           /* Restriction (4)  */
  if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){
     return 0;         /* Restrictions (8)(9) */

** found, add it to the pConst structure.
*/
static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
  Expr *pRight, *pLeft;
  if( pExpr==0 ) return;
  if( ExprHasProperty(pExpr, EP_FromJoin) ) return;
  if( pExpr->op==TK_AND ){
    assert( pExpr->eX==EX_Right );
    findConstInWhere(pConst, pExpr->x.pRight);
    findConstInWhere(pConst, pExpr->pLeft);
    return;
  }
  if( pExpr->op!=TK_EQ ) return;
  assert( pExpr->eX==EX_Right );
  pRight = pExpr->x.pRight;
  pLeft = pExpr->pLeft;
  assert( pRight!=0 );
  assert( pLeft!=0 );
  if( pRight->op==TK_COLUMN
   && !ExprHasProperty(pRight, EP_FixedCol)
   && sqlite3ExprIsConstant(pLeft)
   && sqlite3IsBinary(sqlite3ComparisonCollSeq(pConst->pParse,pLeft,pRight))
  ){
    constInsert(pConst, pRight, pLeft);
  }else
  if( pLeft->op==TK_COLUMN
   && !ExprHasProperty(pLeft, EP_FixedCol)
   && sqlite3ExprIsConstant(pRight)
   && sqlite3IsBinary(sqlite3ComparisonCollSeq(pConst->pParse,pLeft,pRight))
  ){
    constInsert(pConst, pLeft, pRight);
  }
}

/*
** This is a Walker expression callback.  pExpr is a candidate expression

  }
#endif

  if( pSubq->pLimit!=0 ){
    return 0; /* restriction (3) */
  }
  while( pWhere->op==TK_AND ){
    assert( pWhere->eX==EX_Right );
    nChng += pushDownWhereTerms(pParse, pSubq, pWhere->x.pRight,
                                iCursor, isLeftJoin);
    pWhere = pWhere->pLeft;
  }
  if( isLeftJoin
   && (ExprHasProperty(pWhere,EP_FromJoin)==0
         || pWhere->iRightJoinTable!=iCursor)
  ){

  **
  ** The first loop just checks to see if there are any "*" operators
  ** that need expanding.
  */
  for(k=0; k<pEList->nExpr; k++){
    pE = pEList->a[k].pExpr;
    if( pE->op==TK_ASTERISK ) break;
    assert( pE->op!=TK_DOT || pE->eX==EX_Right );
    assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) );
    if( pE->op==TK_DOT && pE->x.pRight->op==TK_ASTERISK ) break;
    elistFlags |= pE->flags;
  }
  if( k<pEList->nExpr ){
    /*
    ** If we get here it means the result set contains one or more "*"
    ** operators that need to be expanded.  Loop through each expression
    ** in the result set and expand them one by one.
    */
    struct ExprList_item *a = pEList->a;
    ExprList *pNew = 0;
    int flags = pParse->db->flags;
    int longNames = (flags & SQLITE_FullColNames)!=0
                      && (flags & SQLITE_ShortColNames)==0;

    for(k=0; k<pEList->nExpr; k++){
      pE = a[k].pExpr;
      elistFlags |= pE->flags;
      pRight = pE->eX==EX_Right ? pE->x.pRight : 0;
      assert( pE->op!=TK_DOT || pRight!=0 );
      if( pE->op!=TK_ASTERISK
       && (pE->op!=TK_DOT || pRight->op!=TK_ASTERISK)
      ){
        /* This particular expression does not need to be expanded.
        */
        pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr);

         && pAggInfo->aFunc[i].iMem<=pAggInfo->mxReg );
  }
#endif
  sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->mnReg, pAggInfo->mxReg);
  for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
    if( pFunc->iDistinct>=0 ){
      Expr *pE = pFunc->pExpr;
      assert( pE->eX==EX_List || pE->eX==EX_None );
      if( pE->eX==EX_None || pE->x.pList->nExpr!=1 ){
        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
           "argument");
        pFunc->iDistinct = -1;
      }else{
        KeyInfo *pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pE->x.pList,0,0);
        sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
                          (char*)pKeyInfo, P4_KEYINFO);

*/
static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
  Vdbe *v = pParse->pVdbe;
  int i;
  struct AggInfo_func *pF;
  for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
    ExprList *pList = pF->pExpr->x.pList;
    assert( pF->pExpr->eX==EX_List || pF->pExpr->eX==EX_None );
    assert( pF->pExpr->eX==EX_List || pList==0 );
    sqlite3VdbeAddOp2(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0);
    sqlite3VdbeAppendP4(v, pF->pFunc, P4_FUNCDEF);
  }
}


/*

  pAggInfo->directMode = 1;
  for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
    int nArg;
    int addrNext = 0;
    int regAgg;
    ExprList *pList = pF->pExpr->x.pList;
    assert( pF->pExpr->eX==EX_List || pF->pExpr->eX==EX_None );
    if( pList ){
      nArg = pList->nExpr;
      regAgg = sqlite3GetTempRange(pParse, nArg);
      sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP);
    }else{
      nArg = 0;
      regAgg = 0;

    sAggInfo.nAccumulator = sAggInfo.nColumn;
    if( p->pGroupBy==0 && p->pHaving==0 && sAggInfo.nFunc==1 ){
      minMaxFlag = minMaxQuery(db, sAggInfo.aFunc[0].pExpr, &pMinMaxOrderBy);
    }else{
      minMaxFlag = WHERE_ORDERBY_NORMAL;
    }
    for(i=0; i<sAggInfo.nFunc; i++){
      if( sAggInfo.aFunc[i].pExpr->eX==EX_List ){
        sNC.ncFlags |= NC_InAggFunc;
        sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
        sNC.ncFlags &= ~NC_InAggFunc;
      }
    }
    sAggInfo.mxReg = pParse->nMem;
    if( db->mallocFailed ) goto select_end;
#if SELECTTRACE_ENABLED
    if( sqlite3SelectTrace & 0x400 ){
      int ii;
      SELECTTRACE(0x400,pParse,p,("After aggregate analysis:\n"));

** are contained within the same memory allocation.  Note, however, that
** the subtrees in Expr.x.pList or Expr.x.pSelect are always separately
** allocated, regardless of whether or not EP_Reduced is set.
*/
struct Expr {
  u8 op;                 /* Operation performed by this node */
  char affinity;         /* The affinity of the column or 0 if not a column */
  u8 eV;                 /* Which element of v-union is used */
  u8 eX;                 /* Which element of x-union is used */
  u32 flags;             /* Various flags.  EP_* See below */
  union {
    char *zToken;          /* Token value. Zero terminated and dequoted */
    int iValue;            /* Non-negative integer value if EP_IntValue */
  } u;

  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction.
  *********************************************************************/

  Expr *pLeft;           /* Left subnode */

  union {
    Expr *pRight;        /* Right subnode */
    ExprList *pList;     /* op = IN, EXISTS, SELECT, CASE, FUNCTION, BETWEEN */
    Select *pSelect;     /* EP_xIsSelect and op = IN, EXISTS, SELECT */
    Table *pTab;         /* Table for TK_COLUMN expressions. Can be NULL
                         ** for a column of an index on an expression */
  } x;

  /* If the EP_Reduced flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction.
  *********************************************************************/

                         ** TK_SELECT_COLUMN: column of the result vector */
  i16 iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
  i16 iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
  u8 op2;                /* TK_REGISTER: original value of Expr.op
                         ** TK_COLUMN: the value of p5 for OP_Column
                         ** TK_AGG_FUNCTION: nesting depth */
  AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */


#ifndef SQLITE_OMIT_WINDOWFUNC
  Window *pWin;          /* Window definition for window functions */
#endif
};

/*
** Allowed values for the Expr.eV and Expr.eX fields:
*/
#define EV_None     0    /* Expr.v is not used */
#define EV_Left     1    /* Expr.v.pLeft */
#define EV_Vector   2    /* Expr.v.pVector */
#define EV_Win      3    /* Expr.v.pWin */

#define EX_None     0    /* Expr.x is not used */
#define EX_Right    1    /* Expr.x.pRight */
#define EX_List     2    /* Expr.x.pList */
#define EX_Select   3    /* Expr.x.pSelect */
#define EX_Tab      4    /* Expr.x.pTab */

/*
** The following are the meanings of bits in the Expr.flags field.
*/
#define EP_FromJoin  0x000001 /* Originates in ON/USING clause of outer join */
#define EP_Agg       0x000002 /* Contains one or more aggregate functions */
#define EP_HasFunc   0x000004 /* Contains one or more functions of any kind */
#define EP_FixedCol  0x000008 /* TK_Column with a known fixed value */
#define EP_Distinct  0x000010 /* Aggregate function with DISTINCT keyword */
#define EP_VarSelect 0x000020 /* pSelect is correlated, not constant */
#define EP_DblQuoted 0x000040 /* token.z was originally in "..." */
#define EP_InfixFunc 0x000080 /* True for an infix function: LIKE, GLOB, etc */
#define EP_Collate   0x000100 /* Tree contains a TK_COLLATE operator */
#define EP_Generic   0x000200 /* Ignore COLLATE or affinity on this tree */
#define EP_IntValue  0x000400 /* Integer value contained in u.iValue */
/*                   0x000800 -- Available for reuse */
#define EP_Skip      0x001000 /* COLLATE, AS, or UNLIKELY */
#define EP_Reduced   0x002000 /* Expr struct EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly 0x004000 /* Expr struct EXPR_TOKENONLYSIZE bytes only */
#define EP_Static    0x008000 /* Held in memory not obtained from malloc() */
#define EP_MemToken  0x010000 /* Need to sqlite3DbFree() Expr.zToken */
#define EP_NoReduce  0x020000 /* Cannot EXPRDUP_REDUCE this Expr */
#define EP_Unlikely  0x040000 /* unlikely() or likelihood() function */

int sqlite3NoTempsInRange(Parse*,int,int);
#endif
Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
Expr *sqlite3Expr(sqlite3*,int,const char*);
void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);
Expr *sqlite3PExpr(Parse*, int, Expr*, Expr*);
void sqlite3PExprAddSelect(Parse*, Expr*, Select*);
void sqlite3PExprAddExprList(Parse*, Expr*, ExprList*);
void sqlite3ExprAddTab(sqlite3*, Expr*, Table*);
Expr *sqlite3ExprAnd(sqlite3*,Expr*, Expr*);
Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*, int);
void sqlite3ExprAssignVarNumber(Parse*, Expr*, u32);
void sqlite3ExprDelete(sqlite3*, Expr*);
void sqlite3ExprClearXUnion(sqlite3*,Expr*);
ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
ExprList *sqlite3ExprListAppendVector(Parse*,ExprList*,IdList*,Expr*);
void sqlite3ExprListSetSortOrder(ExprList*,int);
void sqlite3ExprListSetName(Parse*,ExprList*,Token*,int);
void sqlite3ExprListSetSpan(Parse*,ExprList*,const char*,const char*);
void sqlite3ExprListDelete(sqlite3*, ExprList*);
u32 sqlite3ExprListFlags(const ExprList*);

FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context*);
int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
void sqlite3ParserReset(Parse*);
int sqlite3Reprepare(Vdbe*);
void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
CollSeq *sqlite3ComparisonCollSeq(Parse*,Expr*,Expr*);
CollSeq *sqlite3ComparisonExprCollSeq(Parse*,Expr*);
int sqlite3TempInMemory(const sqlite3*);
const char *sqlite3JournalModename(int);
#ifndef SQLITE_OMIT_WAL
  int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
  int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);
#endif
#ifndef SQLITE_OMIT_CTE

    }
#endif
    if( p->pOrderBy ){
      sqlite3TreeViewExprList(pView, p->pOrderBy, (n--)>0, "ORDERBY");
    }
    if( p->pLimit ){
      sqlite3TreeViewItem(pView, "LIMIT", (n--)>0);
      sqlite3TreeViewExpr(pView, p->pLimit->pLeft, p->pLimit->eX==EX_Right);
      if( p->pLimit->eX==EX_Right ){
        sqlite3TreeViewItem(pView, "OFFSET", (n--)>0);
        sqlite3TreeViewExpr(pView, p->pLimit->x.pRight, 0);
        sqlite3TreeViewPop(pView);
      }
      sqlite3TreeViewPop(pView);
    }
    if( p->pPrior ){
      const char *zOp = "UNION";
      switch( p->op ){

    case TK_TRUTH: {
      int x;
      const char *azOp[] = {
         "IS-FALSE", "IS-TRUE", "IS-NOT-FALSE", "IS-NOT-TRUE"
      };
      assert( pExpr->op2==TK_IS || pExpr->op2==TK_ISNOT );
      assert( pExpr->eX==EX_Right );
      assert( pExpr->x.pRight->op==TK_TRUEFALSE );
      x = (pExpr->op2==TK_ISNOT)*2 + sqlite3ExprTruthValue(pExpr->x.pRight);
      zUniOp = azOp[x];
      break;
    }

    case TK_SPAN: {
      sqlite3TreeViewLine(pView, "SPAN %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);

      sqlite3TreeViewLine(pView, "SELECT-expr flags=0x%x", pExpr->flags);
      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      break;
    }
    case TK_IN: {
      sqlite3TreeViewLine(pView, "IN flags=0x%x", pExpr->flags);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
      switch( pExpr->eX ){
        case EX_Select: {
          sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
          break;
        }
        case EX_List: {
          sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
          break;
        }
      }
      break;
    }
#endif /* SQLITE_OMIT_SUBQUERY */

    /*
    **    x BETWEEN y AND z

      sqlite3TreeViewLine(pView, "RAISE %s(%Q)", zType, pExpr->u.zToken);
      break;
    }
#endif
    case TK_MATCH: {
      sqlite3TreeViewLine(pView, "MATCH {%d:%d}%s",
                          pExpr->iTable, pExpr->iColumn, zFlgs);
      assert( pExpr->eX==EX_Right );
      sqlite3TreeViewExpr(pView, pExpr->x.pRight, 0);
      break;
    }
    case TK_VECTOR: {
      sqlite3TreeViewBareExprList(pView, pExpr->x.pList, "VECTOR");
      break;
    }
    case TK_SELECT_COLUMN: {

      sqlite3TreeViewLine(pView, "op=%d", pExpr->op);
      break;
    }
  }
  if( zBinOp ){
    sqlite3TreeViewLine(pView, "%s%s", zBinOp, zFlgs);
    sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
    assert( pExpr->eX==EX_Right );
    sqlite3TreeViewExpr(pView, pExpr->x.pRight, 0);
  }else if( zUniOp ){
    sqlite3TreeViewLine(pView, "%s%s", zUniOp, zFlgs);
    sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
  }
  sqlite3TreeViewPop(pView);
}

      sqlite3_str_appendf(p, "%s", "expr");
      break;
  }

  if( zOp ){
    sqlite3_str_appendf(p, "%s(", zOp);
    displayP4Expr(p, pExpr->pLeft);
    if( pExpr->eX==EX_Right ){
      sqlite3_str_append(p, ",", 1);
      displayP4Expr(p, pExpr->x.pRight);
    }
    sqlite3_str_append(p, ")", 1);
  }
}
#endif /* VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS) */

  void *pArg = 0;
  FuncDef *pNew;
  int rc = 0;

  /* Check to see the left operand is a column in a virtual table */
  if( NEVER(pExpr==0) ) return pDef;
  if( pExpr->op!=TK_COLUMN ) return pDef;

  if( pExpr->eX!=EX_Tab || (pTab = pExpr->x.pTab)==0 ) return pDef;
  if( !IsVirtual(pTab) ) return pDef;
  pVtab = sqlite3GetVTable(db, pTab)->pVtab;
  assert( pVtab!=0 );
  assert( pVtab->pModule!=0 );
  pMod = (sqlite3_module *)pVtab->pModule;
  if( pMod->xFindFunction==0 ) return pDef;
 

  testcase( ExprHasProperty(pExpr, EP_TokenOnly) );
  testcase( ExprHasProperty(pExpr, EP_Reduced) );
  while(1){
    rc = pWalker->xExprCallback(pWalker, pExpr);
    if( rc ) return rc & WRC_Abort;
    if( !ExprHasProperty(pExpr,(EP_TokenOnly|EP_Leaf)) ){
      if( pExpr->pLeft && walkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort;
      switch( pExpr->eX ){
        case EX_Right: {
          pExpr = pExpr->x.pRight;
          continue;
        }
        case EX_Select: {
          if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort;
          break;
        }
        case EX_List: {
          if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort;
          break;
        }
      }
#ifndef SQLITE_OMIT_WINDOWFUNC
      if( !ExprHasProperty(pExpr, EP_Reduced) && pExpr->pWin ){
        Window *pWin = pExpr->pWin;
        if( sqlite3WalkExprList(pWalker, pWin->pPartition) ) return WRC_Abort;
        if( sqlite3WalkExprList(pWalker, pWin->pOrderBy) ) return WRC_Abort;
        if( sqlite3WalkExpr(pWalker, pWin->pFilter) ) return WRC_Abort;

         && (iColumn!=XN_EXPR
             || sqlite3ExprCompareSkip(pTerm->pExpr->pLeft,
                                       pScan->pIdxExpr,iCur)==0)
         && (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
        ){
          if( (pTerm->eOperator & WO_EQUIV)!=0
           && pScan->nEquiv<ArraySize(pScan->aiCur)
           && ALWAYS(pTerm->pExpr->eX==EX_Right)
           && (pX = sqlite3ExprSkipCollate(pTerm->pExpr->x.pRight))->op
                       ==TK_COLUMN
          ){
            int j;
            for(j=0; j<pScan->nEquiv; j++){
              if( pScan->aiCur[j]==pX->iTable
               && pScan->aiColumn[j]==pX->iColumn ){
                  break;
              }

              CollSeq *pColl;
              Parse *pParse = pWC->pWInfo->pParse;
              pX = pTerm->pExpr;
              if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){
                continue;
              }
              assert(pX->pLeft);
              pColl = sqlite3ComparisonExprCollSeq(pParse, pX);

              if( pColl==0 ) pColl = pParse->db->pDfltColl;
              if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){
                continue;
              }
            }
            if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
             && ALWAYS(pTerm->pExpr->eX==EX_Right)
             && (pX = pTerm->pExpr->x.pRight)->op==TK_COLUMN
             && pX->iTable==pScan->aiCur[0]
             && pX->iColumn==pScan->aiColumn[0]
            ){
              testcase( pTerm->eOperator & WO_IS );
              continue;
            }
            pScan->pWC = pWC;

      Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
      testcase( iCol==BMS-1 );
      testcase( iCol==BMS );
      if( (idxCols & cMask)==0 ){
        Expr *pX = pTerm->pExpr;
        idxCols |= cMask;
        pIdx->aiColumn[n] = pTerm->u.leftColumn;
        pColl = sqlite3ComparisonExprCollSeq(pParse, pX);
        pIdx->azColl[n] = pColl ? pColl->zName : sqlite3StrBINARY;
        n++;
      }
    }
  }
  assert( (u32)n==pLoop->u.btree.nEq );

      assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT );
      assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE );
      assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT );
      assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE );
      assert( pTerm->eOperator&(WO_IN|WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_AUX) );

      if( op & (WO_LT|WO_LE|WO_GT|WO_GE)
       && ALWAYS(pTerm->pExpr->eX==EX_Right)
       && sqlite3ExprIsVector(pTerm->pExpr->x.pRight) 
      ){
        if( i<16 ) mNoOmit |= (1 << i);
        if( op==WO_LT ) pIdxCons[j].op = WO_LE;
        if( op==WO_GT ) pIdxCons[j].op = WO_GE;
      }
    }

  
  sqlite3_value *p1 = 0;          /* Value extracted from pLower */
  sqlite3_value *p2 = 0;          /* Value extracted from pUpper */
  sqlite3_value *pVal = 0;        /* Value extracted from record */

  pColl = sqlite3LocateCollSeq(pParse, p->azColl[nEq]);
  if( pLower ){
    assert( pLower->pExpr->eX==EX_Right );
    rc = sqlite3Stat4ValueFromExpr(pParse, pLower->pExpr->x.pRight, aff, &p1);
    nLower = 0;
  }
  if( pUpper && rc==SQLITE_OK ){
    assert( pUpper->pExpr->eX==EX_Right );
    rc = sqlite3Stat4ValueFromExpr(pParse, pUpper->pExpr->x.pRight, aff, &p2);
    nUpper = p2 ? 0 : p->nSample;
  }

  if( p1 || p2 ){
    int i;
    int nDiff;
    for(i=0; rc==SQLITE_OK && i<p->nSample; i++){

        SWAP(WhereTerm*, pLower, pUpper);
        SWAP(int, nBtm, nTop);
      }

      /* If possible, improve on the iLower estimate using ($P:$L). */
      if( pLower ){
        int n;                    /* Values extracted from pExpr */
        Expr *pExpr;
        assert( pLower->pExpr->eX==EX_Right );
        pExpr = pLower->pExpr->x.pRight;
        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nBtm, nEq, &n);
        if( rc==SQLITE_OK && n ){
          tRowcnt iNew;
          u16 mask = WO_GT|WO_LE;
          if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT);
          iLwrIdx = whereKeyStats(pParse, p, pRec, 0, a);
          iNew = a[0] + ((pLower->eOperator & mask) ? a[1] : 0);
          if( iNew>iLower ) iLower = iNew;
          nOut--;
          pLower = 0;
        }
      }

      /* If possible, improve on the iUpper estimate using ($P:$U). */
      if( pUpper ){
        int n;                    /* Values extracted from pExpr */
        Expr *pExpr;
        assert( pUpper->pExpr->eX==EX_Right );
        pExpr = pUpper->pExpr->x.pRight;
        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nTop, nEq, &n);
        if( rc==SQLITE_OK && n ){
          tRowcnt iNew;
          u16 mask = WO_GT|WO_LE;
          if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT);
          iUprIdx = whereKeyStats(pParse, p, pRec, 1, a);
          iNew = a[0] + ((pUpper->eOperator & mask) ? a[1] : 0);

        ** then use the probability provided by the application. */
        pLoop->nOut += pTerm->truthProb;
      }else{
        /* In the absence of explicit truth probabilities, use heuristics to
        ** guess a reasonable truth probability. */
        pLoop->nOut--;
        if( pTerm->eOperator&(WO_EQ|WO_IS) ){
          Expr *pRight;
          assert( pTerm->pExpr->eX==EX_Right );
          pRight = pTerm->pExpr->x.pRight;
          testcase( pTerm->pExpr->op==TK_IS );
          if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
            k = 10;
          }else{
            k = 20;
          }
          if( iReduce<k ) iReduce = k;

  nCmp = MIN(nCmp, (pIdx->nColumn - nEq));
  for(i=1; i<nCmp; i++){
    /* Test if comparison i of pTerm is compatible with column (i+nEq) 
    ** of the index. If not, exit the loop.  */
    char aff;                     /* Comparison affinity */
    char idxaff = 0;              /* Indexed columns affinity */
    CollSeq *pColl;               /* Comparison collation sequence */
    Expr *pLhs;
    Expr *pRhs;
    pLhs = pTerm->pExpr->pLeft->x.pList->a[i].pExpr;
    assert( pTerm->pExpr->eX==EX_Right );
    pRhs = pTerm->pExpr->x.pRight;
    assert( pRhs->eX==EX_Select || pRhs->eX==EX_List );
    if( pRhs->eX==EX_Select ){
      pRhs = pRhs->x.pSelect->pEList->a[i].pExpr;
    }else{
      pRhs = pRhs->x.pList->a[i].pExpr;
    }

    /* Check that the LHS of the comparison is a column reference to
    ** the right column of the right source table. And that the sort

    }

    testcase( pLhs->iColumn==XN_ROWID );
    aff = sqlite3CompareAffinity(pRhs, sqlite3ExprAffinity(pLhs));
    idxaff = sqlite3TableColumnAffinity(pIdx->pTable, pLhs->iColumn);
    if( aff!=idxaff ) break;

    pColl = sqlite3ComparisonCollSeq(pParse, pLhs, pRhs);
    if( pColl==0 ) break;
    if( sqlite3StrICmp(pColl->zName, pIdx->azColl[i+nEq]) ) break;
  }
  return i;
}

/*

        || (pNew->wsFlags & WHERE_COLUMN_NULL)!=0 
        || (pNew->wsFlags & WHERE_COLUMN_IN)!=0 
        || (pNew->wsFlags & WHERE_SKIPSCAN)!=0 
    );

    if( eOp & WO_IN ){
      Expr *pExpr = pTerm->pExpr;
      switch( pExpr->eX ){
        case EX_Select: {
          /* "x IN (SELECT ...)":  TUNING: the SELECT returns 25 rows */
          int i;
          nIn = 46;  assert( 46==sqlite3LogEst(25) );
  
          /* The expression may actually be of the form (x, y) IN (SELECT...).
          ** In this case there is a separate term for each of (x) and (y).
          ** However, the nIn multiplier should only be applied once, not once
          ** for each such term. The following loop checks that pTerm is the
          ** first such term in use, and sets nIn back to 0 if it is not. */
          for(i=0; i<pNew->nLTerm-1; i++){
            if( pNew->aLTerm[i] && pNew->aLTerm[i]->pExpr==pExpr ) nIn = 0;
          }
          break;
        }
        case EX_List: {
          /* "x IN (value, value, ...)" */
          nIn = sqlite3LogEst(pExpr->x.pList->nExpr);
          assert( nIn>0 );  /* RHS always has 2 or more terms...  The parser
                            ** changes "x IN (?)" into "x=?". */
          break;
        }
      }
      if( pProbe->hasStat1 ){
        LogEst M, logK, safetyMargin;
        /* Let:
        **   N = the total number of rows in the table
        **   K = the number of entries on the RHS of the IN operator
        **   M = the number of rows in the table that match terms to the 

        pNew->nOut -= nIn;
      }else{
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
        tRowcnt nOut = 0;
        if( nInMul==0 
         && pProbe->nSample 
         && pNew->u.btree.nEq<=pProbe->nSampleCol
         && ((eOp & WO_IN)==0 || pTerm->pExpr->eX==EX_List)
         && OptimizationEnabled(db, SQLITE_Stat34)
        ){
          Expr *pExpr = pTerm->pExpr;
          if( (eOp & (WO_EQ|WO_IS))!=0 ){
            testcase( eOp & WO_EQ );
            testcase( eOp & WO_IS );
            testcase( eOp & WO_ISNULL );
            assert( pExpr->eX==EX_Right );
            rc = whereEqualScanEst(pParse, pBuilder, pExpr->x.pRight, &nOut);
          }else if( pExpr->eX==EX_List ){
            rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut);
          }
          if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
          if( rc!=SQLITE_OK ) break;          /* Jump out of the pTerm loop */
          if( nOut ){
            pNew->nOut = sqlite3LogEst(nOut);
            if( pNew->nOut>saved_nOut ) pNew->nOut = saved_nOut;

*/
static int whereUsablePartialIndex(int iTab, WhereClause *pWC, Expr *pWhere){
  int i;
  WhereTerm *pTerm;
  Parse *pParse = pWC->pWInfo->pParse;
  while( pWhere->op==TK_AND ){
    if( !whereUsablePartialIndex(iTab,pWC,pWhere->pLeft) ) return 0;
    assert( pWhere->eX==EX_Right );
    pWhere = pWhere->x.pRight;
  }
  if( pParse->db->flags & SQLITE_EnableQPSG ) pParse = 0;
  for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
    Expr *pExpr = pTerm->pExpr;
    if( (!ExprHasProperty(pExpr, EP_FromJoin) || pExpr->iRightJoinTable==iTab)
     && sqlite3ExprImpliesExpr(pParse, pExpr, pWhere, iTab) 
    ){

  HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1];
  const char *zRet = 0;
  if( iCons>=0 && iCons<pIdxInfo->nConstraint ){
    CollSeq *pC = 0;
    int iTerm = pIdxInfo->aConstraint[iCons].iTermOffset;
    Expr *pX = pHidden->pWC->a[iTerm].pExpr;
    if( pX->pLeft ){
      pC = sqlite3ComparisonExprCollSeq(pHidden->pParse,pX);
    }
    zRet = (pC ? pC->zName : sqlite3StrBINARY);
  }
  return zRet;
}

/*

        assert( pOrigLhs->a[iField].pExpr!=0 );
        pLhs = sqlite3ExprListAppend(pParse, pLhs, pOrigLhs->a[iField].pExpr);
        pOrigLhs->a[iField].pExpr = 0;
      }
    }
    sqlite3ExprListDelete(db, pOrigRhs);
    sqlite3ExprListDelete(db, pOrigLhs);
    assert( pNew->pLeft->eX==EX_List );
    pNew->pLeft->x.pList = pLhs;
    if( pLhs==0 ) pNew->pLeft->eX = EX_None;
    pNew->x.pSelect->pEList = pRhs;
    if( pLhs && pLhs->nExpr==1 ){
      /* Take care here not to generate a TK_VECTOR containing only a
      ** single value. Since the parser never creates such a vector, some
      ** of the subroutines do not handle this case.  */
      Expr *p = pLhs->a[0].pExpr;
      pLhs->a[0].pExpr = 0;

  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( pLevel->pWLoop->aLTerm[iEq]==pTerm );
  assert( iTarget>0 );
  if( pX->op==TK_EQ || pX->op==TK_IS ){
    assert( pX->eX==EX_Right );
    iReg = sqlite3ExprCodeTarget(pParse, pX->x.pRight, iTarget);
  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType = IN_INDEX_NOOP;
    int iTab;

      }
    }
    for(i=iEq;i<pLoop->nLTerm; i++){
      assert( pLoop->aLTerm[i]!=0 );
      if( pLoop->aLTerm[i]->pExpr==pX ) nEq++;
    }

    if( pX->eX!=EX_Select || pX->x.pSelect->pEList->nExpr==1 ){
      eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, 0);
    }else{
      sqlite3 *db = pParse->db;
      pX = removeUnindexableInClauseTerms(pParse, iEq, pLoop, pX);

      if( !db->mallocFailed ){
        aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*nEq);

        sqlite3ReleaseTempReg(pParse, regBase);
        regBase = r1;
      }else{
        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    if( pTerm->eOperator & WO_IN ){
      if( pTerm->pExpr->eX==EX_Select ){
        /* No affinity ever needs to be (or should be) applied to a value
        ** from the RHS of an "? IN (SELECT ...)" expression. The 
        ** sqlite3FindInIndex() routine has already ensured that the 
        ** affinity of the comparison has been applied to the value.  */
        if( zAff ) zAff[j] = SQLITE_AFF_BLOB;
      }
    }else if( (pTerm->eOperator & WO_ISNULL)==0 ){
      Expr *pRight;
      assert( pTerm->pExpr->eX==EX_Right );
      pRight = pTerm->pExpr->x.pRight;
      if( (pTerm->wtFlags & TERM_IS)==0 && sqlite3ExprCanBeNull(pRight) ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
        VdbeCoverage(v);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_BLOB ){
          zAff[j] = SQLITE_AFF_BLOB;

** this case, generate code to evaluate the expression and leave the
** result in register iReg.
*/
static void codeExprOrVector(Parse *pParse, Expr *p, int iReg, int nReg){
  assert( nReg>0 );
  if( p && sqlite3ExprIsVector(p) ){
#ifndef SQLITE_OMIT_SUBQUERY
    if( p->eX==EX_Select ){
      Vdbe *v = pParse->pVdbe;
      int iSelect = sqlite3CodeSubselect(pParse, p, 0, 0);
      sqlite3VdbeAddOp3(v, OP_Copy, iSelect, iReg, nReg-1);
    }else
#endif
    {
      int i;

*/
static int whereIndexExprTransNode(Walker *p, Expr *pExpr){
  IdxExprTrans *pX = p->u.pIdxTrans;
  if( sqlite3ExprCompare(0, pExpr, pX->pIdxExpr, pX->iTabCur)==0 ){
    pExpr->op = TK_COLUMN;
    pExpr->iTable = pX->iIdxCur;
    pExpr->iColumn = pX->iIdxCol;
    /* pExpr->pTab = 0; */
    return WRC_Prune;
  }else{
    return WRC_Continue;
  }
}

/*

      int iTarget = iReg+j+2;
      pTerm = pLoop->aLTerm[j];
      if( NEVER(pTerm==0) ) continue;
      if( pTerm->eOperator & WO_IN ){
        codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
        addrNotFound = pLevel->addrNxt;
      }else{
        Expr *pExpr = pTerm->pExpr;
        Expr *pRight = pExpr->eX==EX_Right ? pExpr->x.pRight : 0;
        codeExprOrVector(pParse, pRight, iTarget, 1);
      }
    }
    sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg);
    sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1);
    sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg,
                      pLoop->u.vtab.idxStr,

        /* Generate code that will continue to the next row if 
        ** the IN constraint is not satisfied */
        pCompare = sqlite3PExpr(pParse, TK_EQ, 0, 0);
        assert( pCompare!=0 || db->mallocFailed );
        if( pCompare ){
          pCompare->pLeft = pTerm->pExpr->pLeft;
          assert( pCompare->eX==EX_None );
          pRight = sqlite3Expr(db, TK_REGISTER, 0);
          if( pRight ){
            pCompare->x.pRight = pRight;
            pCompare->eX = EX_Right;
            pRight->iTable = iReg+j+2;
            sqlite3ExprIfFalse(pParse, pCompare, pLevel->addrCont, 0);
          }
          pCompare->pLeft = 0;
          sqlite3ExprDelete(db, pCompare);
        }
      }

      assert( TK_GE==TK_GT+3 );      /*  ... is correcct. */

      assert( (pStart->wtFlags & TERM_VNULL)==0 );
      testcase( pStart->wtFlags & TERM_VIRTUAL );
      pX = pStart->pExpr;
      assert( pX!=0 );
      testcase( pStart->leftCursor!=iCur ); /* transitive constraints */
      assert( pX->eX==EX_Right );
      if( sqlite3ExprIsVector(pX->x.pRight) ){
        r1 = rTemp = sqlite3GetTempReg(pParse);
        codeExprOrVector(pParse, pX->x.pRight, r1, 1);
        testcase( pX->op==TK_GT );
        testcase( pX->op==TK_GE );
        testcase( pX->op==TK_LT );
        testcase( pX->op==TK_LE );
        op = aMoveOp[((pX->op - TK_GT - 1) & 0x3) | 0x1];
        assert( pX->op!=TK_GT || op==OP_SeekGE );
        assert( pX->op!=TK_GE || op==OP_SeekGE );
        assert( pX->op!=TK_LT || op==OP_SeekLE );
        assert( pX->op!=TK_LE || op==OP_SeekLE );
      }else{
        r1 = sqlite3ExprCodeTemp(pParse, pX->x.pRight, &rTemp);
        disableTerm(pLevel, pStart);
        op = aMoveOp[(pX->op - TK_GT)];
      }
      sqlite3VdbeAddOp3(v, op, iCur, addrBrk, r1);
      VdbeComment((v, "pk"));
      VdbeCoverageIf(v, pX->op==TK_GT);
      VdbeCoverageIf(v, pX->op==TK_LE);
      VdbeCoverageIf(v, pX->op==TK_LT);
      VdbeCoverageIf(v, pX->op==TK_GE);
      sqlite3ReleaseTempReg(pParse, rTemp);
    }else{
      sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrHalt);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
    }
    if( pEnd ){
      Expr *pX;
      pX = pEnd->pExpr;
      assert( pX!=0 );
      assert( pX->eX==EX_Right );
      assert( (pEnd->wtFlags & TERM_VNULL)==0 );
      testcase( pEnd->leftCursor!=iCur ); /* Transitive constraints */
      testcase( pEnd->wtFlags & TERM_VIRTUAL );
      memEndValue = ++pParse->nMem;
      codeExprOrVector(pParse, pX->x.pRight, memEndValue, 1);
      if( 0==sqlite3ExprIsVector(pX->x.pRight) 
       && (pX->op==TK_LT || pX->op==TK_GT) 
      ){
        testOp = bRev ? OP_Le : OP_Ge;
      }else{
        testOp = bRev ? OP_Lt : OP_Gt;
      }
      if( 0==sqlite3ExprIsVector(pX->x.pRight) ){
        disableTerm(pLevel, pEnd);
      }
    }
    start = sqlite3VdbeCurrentAddr(v);
    pLevel->op = bRev ? OP_Prev : OP_Next;
    pLevel->p1 = iCur;
    pLevel->p2 = start;

    startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
    endEq =   !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
    start_constraints = pRangeStart || nEq>0;

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight;
      assert( pRangeStart->pExpr->eX==EX_Right );
      pRight = pRangeStart->pExpr->x.pRight;
      codeExprOrVector(pParse, pRight, regBase+nEq, nBtm);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
      if( (pRangeStart->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);

    }

    /* Load the value for the inequality constraint at the end of the
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight;
      assert( pRangeEnd->pExpr->eX==EX_Right );
      pRight = pRangeEnd->pExpr->x.pRight;
      codeExprOrVector(pParse, pRight, regBase+nEq, nTop);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);

    assert( !ExprHasProperty(pE, EP_FromJoin) );
    assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
    pAlt = sqlite3WhereFindTerm(pWC, iCur, pTerm->u.leftColumn, notReady,
                    WO_EQ|WO_IN|WO_IS, 0);
    if( pAlt==0 ) continue;
    if( pAlt->wtFlags & (TERM_CODED) ) continue;
    if( (pAlt->eOperator & WO_IN) 
     && (pAlt->pExpr->eX==EX_Select)
     && (pAlt->pExpr->x.pSelect->pEList->nExpr>1)
    ){
      continue;
    }
    testcase( pAlt->eOperator & WO_EQ );
    testcase( pAlt->eOperator & WO_IS );
    testcase( pAlt->eOperator & WO_IN );

** that the collating sequence does not change.  For example:
** "Y collate NOCASE op X" becomes "X op Y" because any collation sequence on
** the left hand side of a comparison overrides any collation sequence 
** attached to the right. For the same reason the EP_Collate flag
** is not commuted.
*/
static void exprCommute(Parse *pParse, Expr *pExpr){
  u16 expRight, expLeft;
  assert( pExpr->eX==EX_Right );
  expRight = (pExpr->x.pRight->flags & EP_Collate);
  expLeft = (pExpr->pLeft->flags & EP_Collate);
  assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
  if( expRight==expLeft ){
    /* Either X and Y both have COLLATE operator or neither do */
    if( expRight ){
      /* Both X and Y have COLLATE operators.  Make sure X is always
      ** used by clearing the EP_Collate flag from Y. */
      pExpr->x.pRight->flags &= ~EP_Collate;
    }else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){
      /* Neither X nor Y have COLLATE operators, but X has a non-default
      ** collating sequence.  So add the EP_Collate marker on X to cause
      ** it to be searched first. */
      pExpr->pLeft->flags |= EP_Collate;
    }
  }
  SWAP(Expr*,pExpr->x.pRight,pExpr->pLeft);
  if( pExpr->op>=TK_GT ){
    assert( TK_LT==TK_GT+2 );
    assert( TK_GE==TK_LE+2 );
    assert( TK_GT>TK_EQ );
    assert( TK_GT<TK_LE );
    assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
    pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;

        ** be converted into "x<0", which is incorrect.
        */
        if( sqlite3Isdigit(zNew[0])
         || zNew[0]=='-'
         || (zNew[0]+1=='0' && iTo==1)
        ){
          if( pLeft->op!=TK_COLUMN 
           || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT
           || NEVER(pLeft->eX!=EX_Tab)
           || IsVirtual(pLeft->x.pTab)  /* Value might be numeric */
          ){
            sqlite3ExprDelete(db, pPrefix);
            sqlite3ValueFree(pVal);
            return 0;
          }
        }
      }

    ** virtual table on their second argument, which is the same as
    ** the left-hand side operand in their in-fix form.
    **
    **       vtab_column MATCH expression
    **       MATCH(expression,vtab_column)
    */
    pCol = pList->a[1].pExpr;
    if( pCol->op==TK_COLUMN && pCol->eX==EX_Tab && IsVirtual(pCol->x.pTab) ){
      for(i=0; i<ArraySize(aOp); i++){
        if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
          *peOp2 = aOp[i].eOp2;
          *ppRight = pList->a[0].pExpr;
          *ppLeft = pCol;
          return 1;
        }

    **      OVERLOADED(vtab_column,expression)
    **
    ** Historically, xFindFunction expected to see lower-case function
    ** names.  But for this use case, xFindFunction is expected to deal
    ** with function names in an arbitrary case.
    */
    pCol = pList->a[0].pExpr;
    if( pCol->op==TK_COLUMN && pCol->eX==EX_Tab && IsVirtual(pCol->x.pTab) ){
      sqlite3_vtab *pVtab;
      sqlite3_module *pMod;
      void (*xNotUsed)(sqlite3_context*,int,sqlite3_value**);
      void *pNotUsed;
      pVtab = sqlite3GetVTable(db, pCol->x.pTab)->pVtab;
      assert( pVtab!=0 );
      assert( pVtab->pModule!=0 );
      pMod = (sqlite3_module *)pVtab->pModule;
      if( pMod->xFindFunction!=0 ){
        i = pMod->xFindFunction(pVtab,2, pExpr->u.zToken, &xNotUsed, &pNotUsed);
        if( i>=SQLITE_INDEX_CONSTRAINT_FUNCTION ){
          *peOp2 = i;
          *ppRight = pList->a[1].pExpr;
          *ppLeft = pCol;
          return 1;
        }
      }
    }
  }else if( pExpr->op==TK_NE || pExpr->op==TK_ISNOT || pExpr->op==TK_NOTNULL ){
    int res = 0;
    Expr *pLeft = pExpr->pLeft;
    Expr *pRight = 0;
    if( pLeft->op==TK_COLUMN && pLeft->eX==EX_Tab && IsVirtual(pLeft->x.pTab) ){
      res++;
    }
    if( pExpr->eX==EX_Right && (pRight = pExpr->x.pRight)->op==TK_COLUMN
     && pRight->eX==EX_Tab && IsVirtual(pRight->x.pTab) ){
      res++;
      SWAP(Expr*, pLeft, pRight);
    }
    *ppLeft = pLeft;
    *ppRight = pRight;
    if( pExpr->op==TK_NE ) *peOp2 = SQLITE_INDEX_CONSTRAINT_NE;
    if( pExpr->op==TK_ISNOT ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOT;

  int op;                /* Operator for the combined expression */
  int idxNew;            /* Index in pWC of the next virtual term */

  if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
  if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
  if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
   && (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return;
  assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->eX==EX_Right );
  assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->eX==EX_Right );
  if( sqlite3ExprCompare(0,pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ){
    return;
  }
  if( sqlite3ExprCompare(0,pOne->pExpr->x.pRight, pTwo->pExpr->x.pRight,-1) ){
    return;
  }
  /* If we reach this point, it means the two subterms can be combined */
  if( (eOp & (eOp-1))!=0 ){
    if( eOp & (WO_LT|WO_LE) ){
      eOp = WO_LE;
    }else{
      assert( eOp & (WO_GT|WO_GE) );
      eOp = WO_GE;

          okToChngToIN = 0;
        }else{
          int affLeft, affRight;
          /* If the right-hand side is also a column, then the affinities
          ** of both right and left sides must be such that no type
          ** conversions are required on the right.  (Ticket #2249)
          */
          assert( pOrTerm->pExpr->eX==EX_Right );
          affRight = sqlite3ExprAffinity(pOrTerm->pExpr->x.pRight);
          affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
          if( affRight!=0 && affRight!=affLeft ){
            okToChngToIN = 0;
          }else{
            pOrTerm->wtFlags |= TERM_OR_OK;
          }
        }

      Expr *pNew;            /* The complete IN operator */

      for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
        if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
        assert( pOrTerm->eOperator & WO_EQ );
        assert( pOrTerm->leftCursor==iCursor );
        assert( pOrTerm->u.leftColumn==iColumn );
        assert( pOrTerm->pExpr->eX==EX_Right );
        pDup = sqlite3ExprDup(db, pOrTerm->pExpr->x.pRight, 0);
        pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup);
        pLeft = pOrTerm->pExpr->pLeft;
      }
      assert( pLeft!=0 );
      pDup = sqlite3ExprDup(db, pLeft, 0);
      pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0);
      if( pNew && pList ){
        int idxNew;
        transferJoinMarkings(pNew, pExpr);
        assert( pNew->eX==EX_None );
        pNew->eX = EX_List;
        pNew->x.pList = pList;
        idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
        testcase( idxNew==0 );
        exprAnalyze(pSrc, pWC, idxNew);
        /* pTerm = &pWC->a[idxTerm]; // would be needed if pTerm used again */
        markTermAsChild(pWC, idxNew, idxTerm);
      }else{
        sqlite3ExprListDelete(db, pList);
        sqlite3ExprDelete(db, pNew);
      }
    }
  }
}
#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */

/*

static int termIsEquivalence(Parse *pParse, Expr *pExpr){
  char aff1, aff2;
  CollSeq *pColl;
  if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0;
  if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0;
  if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0;
  aff1 = sqlite3ExprAffinity(pExpr->pLeft);
  assert( pExpr->eX==EX_Right );
  aff2 = sqlite3ExprAffinity(pExpr->x.pRight);
  if( aff1!=aff2
   && (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2))
  ){
    return 0;
  }
  pColl = sqlite3ComparisonExprCollSeq(pParse, pExpr);
  if( sqlite3IsBinary(pColl) ) return 1;
  return sqlite3ExprCollSeqMatch(pParse, pExpr->pLeft, pExpr->x.pRight);
}

/*
** Recursively walk the expressions of a SELECT statement and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/

  pTerm = &pWC->a[idxTerm];
  pMaskSet = &pWInfo->sMaskSet;
  pExpr = pTerm->pExpr;
  assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
  prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
  op = pExpr->op;
  if( op==TK_IN ){
    assert( pExpr->eX!=EX_Right );
    if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
    switch( pExpr->eX ){
      case EX_Select: {
        pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect);
        break;
      }
      case EX_List: {
        pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet,pExpr->x.pList);
        break;
      }
    }
  }else{
    assert( op!=TK_ISNULL || pExpr->eX!=EX_Right );
    if( pExpr->eX==EX_Right ){
      pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->x.pRight);
    }else{
      pTerm->prereqRight = 0;
    }
  }
  pMaskSet->bVarSelect = 0;
  prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
  if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
  if( ExprHasProperty(pExpr, EP_FromJoin) ){
    Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
    prereqAll |= x;
    extraRight = x-1;  /* ON clause terms may not be used with an index
                       ** on left table of a LEFT JOIN.  Ticket #3015 */
    if( (prereqAll>>1)>=x ){
      sqlite3ErrorMsg(pParse, "ON clause references tables to its right");
      return;
    }
  }
  pTerm->prereqAll = prereqAll;
  pTerm->leftCursor = -1;
  pTerm->iParent = -1;
  pTerm->eOperator = 0;
  if( allowedOp(op) ){
    int aiCurCol[2];
    Expr *pLeft, *pRight;
    u16 opMask;

    pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
    if( pExpr->eX==EX_Right ){
      pRight = sqlite3ExprSkipCollate(pExpr->x.pRight);
    }else{
      pRight = 0;
    }
    opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
    if( pTerm->iField>0 ){
      assert( op==TK_IN );
      assert( pLeft->op==TK_VECTOR );
      pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
    }

    if( exprMightBeIndexed(pSrc, prereqLeft, aiCurCol, pLeft, op) ){

  ** no longer used.
  **
  ** This is only required if at least one side of the comparison operation
  ** is not a sub-select.  */
  if( pWC->op==TK_AND 
  && (pExpr->op==TK_EQ || pExpr->op==TK_IS)
  && (nLeft = sqlite3ExprVectorSize(pExpr->pLeft))>1
  && ALWAYS(pExpr->eX==EX_Right)
  && sqlite3ExprVectorSize(pExpr->x.pRight)==nLeft
  && ( pExpr->pLeft->eX!=EX_Select || pExpr->x.pRight->eX!=EX_Select )

  ){
    int i;
    for(i=0; i<nLeft; i++){
      int idxNew;
      Expr *pNew, *pLeft, *pRight;

      pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
      assert( pExpr->eX==EX_Right );
      pRight = sqlite3ExprForVectorField(pParse, pExpr->x.pRight, i);

      pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight);
      transferJoinMarkings(pNew, pExpr);
      idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
      exprAnalyze(pSrc, pWC, idxNew);
    }
    pTerm = &pWC->a[idxTerm];
    pTerm->wtFlags |= TERM_CODED|TERM_VIRTUAL;  /* Disable the original */

void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
  Expr *pE2 = sqlite3ExprSkipCollate(pExpr);
  pWC->op = op;
  if( pE2==0 ) return;
  if( pE2->op!=op ){
    whereClauseInsert(pWC, pExpr, 0);
  }else{
    assert( pE2->eX==EX_Right );
    sqlite3WhereSplit(pWC, pE2->pLeft, op);
    sqlite3WhereSplit(pWC, pE2->x.pRight, op);
  }
}

/*
** Initialize a preallocated WhereClause structure.
*/
void sqlite3WhereClauseInit(

    return sqlite3WhereGetMask(pMaskSet, p->iTable);
  }else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
    assert( p->op!=TK_IF_NULL_ROW );
    return 0;
  }
  mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;
  if( p->pLeft ) mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pLeft);
  switch( p->eX ){
    case EX_Right: {
      mask |= sqlite3WhereExprUsageNN(pMaskSet, p->x.pRight);

      break;
    }
    case EX_Select: {
      if( ExprHasProperty(p, EP_VarSelect) ) pMaskSet->bVarSelect = 1;
      mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
      break;
    }
    case EX_List: {
      mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
      break;
    }
  }
  return mask;
}
Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
  return p ? sqlite3WhereExprUsageNN(pMaskSet,p) : 0;
}
Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){

                      pTab->zName, j);
      return;
    }
    pColRef = sqlite3ExprAlloc(pParse->db, TK_COLUMN, 0, 0);
    if( pColRef==0 ) return;
    pColRef->iTable = pItem->iCursor;
    pColRef->iColumn = k++;
    pColRef->x.pTab = pTab;
    pColRef->eX = EX_Tab;
    pTerm = sqlite3PExpr(pParse, TK_EQ, pColRef,
                         sqlite3ExprDup(pParse->db, pArgs->a[j].pExpr, 0));
    whereClauseInsert(pWC, pTerm, TERM_DYNAMIC);
  }
}

#***********************************************************************
# Test the virtual table interface. In particular the xBestIndex
# method.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix bestindex5

ifcapable !vtab {
  finish_test
  return
}

#-------------------------------------------------------------------------

do_execsql_test 3.3 { SELECT rowid, * FROM t4 WHERE x!=245; } {}
do_execsql_test 3.4 { SELECT rowid, * FROM t4 WHERE x!='245'; } {}

do_execsql_test 3.5 { SELECT rowid, * FROM t4 WHERE rowid!=1 OR x!='245'; } {}


finish_test