**    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 1.112 2002/09/08 17:23:43 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqliteSelectNew(
  ExprList *pEList,     /* which columns to include in the result */
................................................................................
    case TK_INTERSECT: z = "INTERSECT";   break;
    case TK_EXCEPT:    z = "EXCEPT";      break;
    default:           z = "UNION";       break;
  }
  return z;
}






/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqliteResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){
  Table *pTab;
  int i;
  ExprList *pEList;
  static int fillInColumnList(Parse*, Select*);

  if( fillInColumnList(pParse, pSelect) ){
    return 0;
  }
  pTab = sqliteMalloc( sizeof(Table) );
  if( pTab==0 ){
    return 0;
................................................................................
}

/*
** Recursively scan through an expression tree.  For every reference
** to a column in table number iFrom, change that reference to the
** same column in table number iTo.
*/

static void changeTables(Expr *pExpr, int iFrom, int iTo){
  if( pExpr==0 ) return;
  if( pExpr->op==TK_COLUMN && pExpr->iTable==iFrom ){
    pExpr->iTable = iTo;
  }else{
    static void changeTablesInList(ExprList*, int, int);
    changeTables(pExpr->pLeft, iFrom, iTo);
    changeTables(pExpr->pRight, iFrom, iTo);
    changeTablesInList(pExpr->pList, iFrom, iTo);
  }
}
static void changeTablesInList(ExprList *pList, int iFrom, int iTo){
  if( pList ){
................................................................................
** This routine is part of the flattening procedure.  A subquery
** whose result set is defined by pEList appears as entry in the
** FROM clause of a SELECT such that the VDBE cursor assigned to that
** FORM clause entry is iTable.  This routine make the necessary 
** changes to pExpr so that it refers directly to the source table
** of the subquery rather the result set of the subquery.
*/

static void substExpr(Expr *pExpr, int iTable, ExprList *pEList, int iSub){
  if( pExpr==0 ) return;
  if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable && pExpr->iColumn>=0 ){
    Expr *pNew;
    assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
    assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 );
    pNew = pEList->a[pExpr->iColumn].pExpr;
................................................................................
    pExpr->iAgg = pNew->iAgg;
    pExpr->nFuncName = pNew->nFuncName;
    sqliteTokenCopy(&pExpr->token, &pNew->token);
    if( iSub!=iTable ){
      changeTables(pExpr, iSub, iTable);
    }
  }else{
    static void substExprList(ExprList*,int,ExprList*,int);
    substExpr(pExpr->pLeft, iTable, pEList, iSub);
    substExpr(pExpr->pRight, iTable, pEList, iSub);
    substExprList(pExpr->pList, iTable, pEList, iSub);
  }
}
static void 
substExprList(ExprList *pList, int iTable, ExprList *pEList, int iSub){

**    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 1.113 2002/10/20 15:53:04 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqliteSelectNew(
  ExprList *pEList,     /* which columns to include in the result */
................................................................................
    case TK_INTERSECT: z = "INTERSECT";   break;
    case TK_EXCEPT:    z = "EXCEPT";      break;
    default:           z = "UNION";       break;
  }
  return z;
}

/*
** Forward declaration
*/
static int fillInColumnList(Parse*, Select*);

/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqliteResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){
  Table *pTab;
  int i;
  ExprList *pEList;


  if( fillInColumnList(pParse, pSelect) ){
    return 0;
  }
  pTab = sqliteMalloc( sizeof(Table) );
  if( pTab==0 ){
    return 0;
................................................................................
}

/*
** Recursively scan through an expression tree.  For every reference
** to a column in table number iFrom, change that reference to the
** same column in table number iTo.
*/
static void changeTablesInList(ExprList*, int, int);  /* Forward Declaration */
static void changeTables(Expr *pExpr, int iFrom, int iTo){
  if( pExpr==0 ) return;
  if( pExpr->op==TK_COLUMN && pExpr->iTable==iFrom ){
    pExpr->iTable = iTo;
  }else{

    changeTables(pExpr->pLeft, iFrom, iTo);
    changeTables(pExpr->pRight, iFrom, iTo);
    changeTablesInList(pExpr->pList, iFrom, iTo);
  }
}
static void changeTablesInList(ExprList *pList, int iFrom, int iTo){
  if( pList ){
................................................................................
** This routine is part of the flattening procedure.  A subquery
** whose result set is defined by pEList appears as entry in the
** FROM clause of a SELECT such that the VDBE cursor assigned to that
** FORM clause entry is iTable.  This routine make the necessary 
** changes to pExpr so that it refers directly to the source table
** of the subquery rather the result set of the subquery.
*/
static void substExprList(ExprList*,int,ExprList*,int);  /* Forward Decl */
static void substExpr(Expr *pExpr, int iTable, ExprList *pEList, int iSub){
  if( pExpr==0 ) return;
  if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable && pExpr->iColumn>=0 ){
    Expr *pNew;
    assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
    assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 );
    pNew = pEList->a[pExpr->iColumn].pExpr;
................................................................................
    pExpr->iAgg = pNew->iAgg;
    pExpr->nFuncName = pNew->nFuncName;
    sqliteTokenCopy(&pExpr->token, &pNew->token);
    if( iSub!=iTable ){
      changeTables(pExpr, iSub, iTable);
    }
  }else{

    substExpr(pExpr->pLeft, iTable, pEList, iSub);
    substExpr(pExpr->pRight, iTable, pEList, iSub);
    substExprList(pExpr->pList, iTable, pEList, iSub);
  }
}
static void 
substExprList(ExprList *pList, int iTable, ExprList *pEList, int iSub){