**    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 1.297 2006/01/21 22:19:55 drh Exp $
*/
#include "sqliteInt.h"



















/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
  ExprList *pEList,     /* which columns to include in the result */
................................................................................
  Expr *pHaving,        /* the HAVING clause */
  ExprList *pOrderBy,   /* the ORDER BY clause */
  int isDistinct,       /* true if the DISTINCT keyword is present */
  Expr *pLimit,         /* LIMIT value.  NULL means not used */
  Expr *pOffset         /* OFFSET value.  NULL means no offset */
){
  Select *pNew;

  pNew = sqliteMalloc( sizeof(*pNew) );
  assert( !pOffset || pLimit );   /* Can't have OFFSET without LIMIT. */
  if( pNew==0 ){
    sqlite3ExprListDelete(pEList);
    sqlite3SrcListDelete(pSrc);
    sqlite3ExprDelete(pWhere);
    sqlite3ExprListDelete(pGroupBy);
    sqlite3ExprDelete(pHaving);
    sqlite3ExprListDelete(pOrderBy);
    sqlite3ExprDelete(pLimit);
    sqlite3ExprDelete(pOffset);
  }else{

    if( pEList==0 ){
      pEList = sqlite3ExprListAppend(0, sqlite3Expr(TK_ALL,0,0,0), 0);
    }
    pNew->pEList = pEList;
    pNew->pSrc = pSrc;
    pNew->pWhere = pWhere;
    pNew->pGroupBy = pGroupBy;
    pNew->pHaving = pHaving;
    pNew->pOrderBy = pOrderBy;
    pNew->isDistinct = isDistinct;
    pNew->op = TK_SELECT;
    pNew->pLimit = pLimit;
    pNew->pOffset = pOffset;
    pNew->iLimit = -1;
    pNew->iOffset = -1;
    pNew->addrOpenVirt[0] = -1;
    pNew->addrOpenVirt[1] = -1;
    pNew->addrOpenVirt[2] = -1;



  }
  return pNew;
}











/*
** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
** type of join.  Return an integer constant that expresses that type
** in terms of the following bit values:
**
**     JT_INNER
................................................................................
                            pRight->iCursor, &p->pWhere);
      }
    }
  }
  return 0;
}

/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(Select *p){
  if( p==0 ) return;
  sqlite3ExprListDelete(p->pEList);
  sqlite3SrcListDelete(p->pSrc);
  sqlite3ExprDelete(p->pWhere);
  sqlite3ExprListDelete(p->pGroupBy);
  sqlite3ExprDelete(p->pHaving);
  sqlite3ExprListDelete(p->pOrderBy);
  sqlite3SelectDelete(p->pPrior);
  sqlite3ExprDelete(p->pLimit);
  sqlite3ExprDelete(p->pOffset);
  sqliteFree(p);
}

/*
** Insert code into "v" that will push the record on the top of the
** stack into the sorter.
*/
static void pushOntoSorter(
  Parse *pParse,         /* Parser context */
  ExprList *pOrderBy,    /* The ORDER BY clause */
................................................................................

  if( v==0 ) return 0;
  assert( pEList!=0 );

  /* If there was a LIMIT clause on the SELECT statement, then do the check
  ** to see if this row should be output.
  */
  hasDistinct = distinct>=0 && pEList && pEList->nExpr>0;
  if( pOrderBy==0 && !hasDistinct ){
    codeOffset(v, p, iContinue, 0);
  }

  /* Pull the requested columns.
  */
  if( nColumn>0 ){

**    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 1.298 2006/01/22 00:42:09 drh Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
*/
void clearSelect(Select *p){
  sqlite3ExprListDelete(p->pEList);
  sqlite3SrcListDelete(p->pSrc);
  sqlite3ExprDelete(p->pWhere);
  sqlite3ExprListDelete(p->pGroupBy);
  sqlite3ExprDelete(p->pHaving);
  sqlite3ExprListDelete(p->pOrderBy);
  sqlite3SelectDelete(p->pPrior);
  sqlite3ExprDelete(p->pLimit);
  sqlite3ExprDelete(p->pOffset);
}


/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
  ExprList *pEList,     /* which columns to include in the result */
................................................................................
  Expr *pHaving,        /* the HAVING clause */
  ExprList *pOrderBy,   /* the ORDER BY clause */
  int isDistinct,       /* true if the DISTINCT keyword is present */
  Expr *pLimit,         /* LIMIT value.  NULL means not used */
  Expr *pOffset         /* OFFSET value.  NULL means no offset */
){
  Select *pNew;
  Select standin;
  pNew = sqliteMalloc( sizeof(*pNew) );
  assert( !pOffset || pLimit );   /* Can't have OFFSET without LIMIT. */
  if( pNew==0 ){

    pNew = &standin;
    memset(pNew, 0, sizeof(*pNew));






  }
  if( pEList==0 ){
    pEList = sqlite3ExprListAppend(0, sqlite3Expr(TK_ALL,0,0,0), 0);
  }
  pNew->pEList = pEList;
  pNew->pSrc = pSrc;
  pNew->pWhere = pWhere;
  pNew->pGroupBy = pGroupBy;
  pNew->pHaving = pHaving;
  pNew->pOrderBy = pOrderBy;
  pNew->isDistinct = isDistinct;
  pNew->op = TK_SELECT;
  pNew->pLimit = pLimit;
  pNew->pOffset = pOffset;
  pNew->iLimit = -1;
  pNew->iOffset = -1;
  pNew->addrOpenVirt[0] = -1;
  pNew->addrOpenVirt[1] = -1;
  pNew->addrOpenVirt[2] = -1;
  if( pNew==&standin) {
    clearSelect(pNew);
    pNew = 0;
  }
  return pNew;
}

/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(Select *p){
  if( p ){
    clearSelect(p);
    sqliteFree(p);
  }
}

/*
** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
** type of join.  Return an integer constant that expresses that type
** in terms of the following bit values:
**
**     JT_INNER
................................................................................
                            pRight->iCursor, &p->pWhere);
      }
    }
  }
  return 0;
}


















/*
** Insert code into "v" that will push the record on the top of the
** stack into the sorter.
*/
static void pushOntoSorter(
  Parse *pParse,         /* Parser context */
  ExprList *pOrderBy,    /* The ORDER BY clause */
................................................................................

  if( v==0 ) return 0;
  assert( pEList!=0 );

  /* If there was a LIMIT clause on the SELECT statement, then do the check
  ** to see if this row should be output.
  */
  hasDistinct = distinct>=0 && pEList->nExpr>0;
  if( pOrderBy==0 && !hasDistinct ){
    codeOffset(v, p, iContinue, 0);
  }

  /* Pull the requested columns.
  */
  if( nColumn>0 ){