SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.475 2008/09/17 00:13:12 drh Exp $
** $Id: select.c,v 1.476 2008/09/23 09:36:10 drh Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

  int regPrev;          /* A range of registers to hold previous output */
  int savedLimit;       /* Saved value of p->iLimit */
  int savedOffset;      /* Saved value of p->iOffset */
  int labelCmpr;        /* Label for the start of the merge algorithm */
  int labelEnd;         /* Label for the end of the overall SELECT stmt */
  int j1;               /* Jump instructions that get retargetted */
  int op;               /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
  KeyInfo *pKeyDup;     /* Comparison information for duplicate removal */
  KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
  KeyInfo *pKeyMerge;   /* Comparison information for merging rows */
  sqlite3 *db;          /* Database connection */
  ExprList *pOrderBy;   /* The ORDER BY clause */
  int nOrderBy;         /* Number of terms in the ORDER BY clause */
  int *aPermute;        /* Mapping from ORDER BY terms to result set columns */

  assert( p->pOrderBy!=0 );
  assert( pKeyDup==0 ); /* "Managed" code needs this.  Ticket #3382. */
  db = pParse->db;
  v = pParse->pVdbe;
  if( v==0 ) return SQLITE_NOMEM;
  labelEnd = sqlite3VdbeMakeLabel(v);
  labelCmpr = sqlite3VdbeMakeLabel(v);