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Comment:The expression "(X IS FALSE) BETWEEN FALSE AND TRUE" does not implie that X is not NULL. Ticket [fba33c8b1df6a915]
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Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 057fb8b1809b8b9c8fff0fd0804153b9644f0545c23c6ddc4758bda3381094b9
User & Date: drh 2019-08-30 15:11:08
Context
2019-08-30
16:00
The expression "(X IS FALSE) IN (FALSE)" does not imply that X is NOT NULL. Ticket [f8f472cbc77ba9c9] check-in: dd66134817 user: drh tags: trunk
15:11
The expression "(X IS FALSE) BETWEEN FALSE AND TRUE" does not implie that X is not NULL. Ticket [fba33c8b1df6a915] check-in: 057fb8b180 user: drh tags: trunk
13:07
The expression "(x IS FALSE) IS FALSE" does not imply that X is not NULL. Ticket [a6408d42b9f44462] check-in: 45ff2b1f26 user: drh tags: trunk
Changes
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Changes to src/expr.c.

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             sqlite3ExprSkipCollateAndLikely(pA),
             sqlite3ExprSkipCollateAndLikely(pB),
             iTab);
}

/*
** Return non-zero if Expr p can only be true if pNN is not NULL.



*/
static int exprImpliesNotNull(
  Parse *pParse,      /* Parsing context */
  Expr *p,            /* The expression to be checked */
  Expr *pNN,          /* The expression that is NOT NULL */
  int iTab,           /* Table being evaluated */
  int seenNot         /* True if p is an operand of NOT */
){
  assert( p );
  assert( pNN );
  if( sqlite3ExprCompare(pParse, p, pNN, iTab)==0 ){
    return pNN->op!=TK_NULL;
  }
  switch( p->op ){
................................................................................
      return exprImpliesNotNull(pParse, p->pLeft, pNN, iTab, seenNot);
    }
    case TK_BETWEEN: {
      ExprList *pList = p->x.pList;
      assert( pList!=0 );
      assert( pList->nExpr==2 );
      if( seenNot ) return 0;
      if( exprImpliesNotNull(pParse, pList->a[0].pExpr, pNN, iTab, seenNot)
       || exprImpliesNotNull(pParse, pList->a[1].pExpr, pNN, iTab, seenNot)
      ){
        return 1;
      }
      return exprImpliesNotNull(pParse, p->pLeft, pNN, iTab, seenNot);
    }
    case TK_EQ:
    case TK_NE:
    case TK_LT:
    case TK_LE:
    case TK_GT:
    case TK_GE:







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             sqlite3ExprSkipCollateAndLikely(pA),
             sqlite3ExprSkipCollateAndLikely(pB),
             iTab);
}

/*
** Return non-zero if Expr p can only be true if pNN is not NULL.
**
** Or if seenNot is true, return non-zero if Expr p can only be
** non-NULL if pNN is not NULL
*/
static int exprImpliesNotNull(
  Parse *pParse,      /* Parsing context */
  Expr *p,            /* The expression to be checked */
  Expr *pNN,          /* The expression that is NOT NULL */
  int iTab,           /* Table being evaluated */
  int seenNot         /* Return true only if p can be any non-NULL value */
){
  assert( p );
  assert( pNN );
  if( sqlite3ExprCompare(pParse, p, pNN, iTab)==0 ){
    return pNN->op!=TK_NULL;
  }
  switch( p->op ){
................................................................................
      return exprImpliesNotNull(pParse, p->pLeft, pNN, iTab, seenNot);
    }
    case TK_BETWEEN: {
      ExprList *pList = p->x.pList;
      assert( pList!=0 );
      assert( pList->nExpr==2 );
      if( seenNot ) return 0;
      if( exprImpliesNotNull(pParse, pList->a[0].pExpr, pNN, iTab, 1)
       || exprImpliesNotNull(pParse, pList->a[1].pExpr, pNN, iTab, 1)
      ){
        return 1;
      }
      return exprImpliesNotNull(pParse, p->pLeft, pNN, iTab, 1);
    }
    case TK_EQ:
    case TK_NE:
    case TK_LT:
    case TK_LE:
    case TK_GT:
    case TK_GE:

Changes to test/index6.test.

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do_execsql_test index6-14.2 {
  SELECT * FROM t0 WHERE CASE c0 WHEN 0 THEN 0 ELSE 1 END;
} {{} row}

# 2019-08-30
# Ticket https://www.sqlite.org/src/info/a6408d42b9f44462

#
do_execsql_test index6-15.1 {
  DROP TABLE t0;
  CREATE TABLE t0(c0);
  INSERT INTO t0(c0) VALUES (NULL);
  CREATE INDEX i0 ON t0(1) WHERE c0 NOT NULL;
  SELECT 1 FROM t0 WHERE (t0.c0 IS FALSE) IS FALSE;
} {1}










finish_test







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do_execsql_test index6-14.2 {
  SELECT * FROM t0 WHERE CASE c0 WHEN 0 THEN 0 ELSE 1 END;
} {{} row}

# 2019-08-30
# Ticket https://www.sqlite.org/src/info/a6408d42b9f44462
# Ticket https://www.sqlite.org/src/info/fba33c8b1df6a915
#
do_execsql_test index6-15.1 {
  DROP TABLE t0;
  CREATE TABLE t0(c0);
  INSERT INTO t0(c0) VALUES (NULL);
  CREATE INDEX i0 ON t0(1) WHERE c0 NOT NULL;
  SELECT 1 FROM t0 WHERE (t0.c0 IS FALSE) IS FALSE;
} {1}
do_execsql_test index6-15.2 {
  SELECT 1 FROM t0 WHERE (t0.c0 IS FALSE) BETWEEN FALSE AND TRUE;
} {1}
do_execsql_test index6-15.3 {
  SELECT 1 FROM t0 WHERE TRUE BETWEEN (t0.c0 IS FALSE) AND TRUE;
} {1}
do_execsql_test index6-15.4 {
  SELECT 1 FROM t0 WHERE FALSE BETWEEN FALSE AND (t0.c0 IS FALSE);
} {1}

finish_test