**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.52 2002/03/02 17:04:08 drh Exp $
*/
#include "sqliteInt.h"


/*
** Construct a new expression node and return a pointer to it.  Memory
** for this node is obtained from sqliteMalloc().  The calling function
................................................................................
}

/*
** Recursively delete an expression tree.
*/
void sqliteExprDelete(Expr *p){
  if( p==0 ) return;
  if( p->op!=TK_AS ){
    if( p->pLeft ) sqliteExprDelete(p->pLeft);
    if( p->pRight ) sqliteExprDelete(p->pRight);
  }
  if( p->pList ) sqliteExprListDelete(p->pList);
  if( p->pSelect ) sqliteSelectDelete(p->pSelect);
  sqliteFree(p);
}

/*
** The following group of functions are used to translate the string
................................................................................
        for(j=0; j<pEList->nExpr; j++){
          char *zAs = pEList->a[j].zName;
          if( zAs!=0 && sqliteStrICmp(zAs, z)==0 ){
            cnt++;
            assert( pExpr->pLeft==0 && pExpr->pRight==0 );
            pExpr->op = TK_AS;
            pExpr->iColumn = j;
            pExpr->pLeft = pEList->a[j].pExpr;
          }
        } 
      }
      if( cnt==0 && sqliteIsRowid(z) ){
        pExpr->iColumn = -1;
        pExpr->iTable = base;
        cnt = 1 + (pTabList->nId>1);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.53 2002/03/03 03:42:31 drh Exp $
*/
#include "sqliteInt.h"


/*
** Construct a new expression node and return a pointer to it.  Memory
** for this node is obtained from sqliteMalloc().  The calling function
................................................................................
}

/*
** Recursively delete an expression tree.
*/
void sqliteExprDelete(Expr *p){
  if( p==0 ) return;

  if( p->pLeft ) sqliteExprDelete(p->pLeft);
  if( p->pRight ) sqliteExprDelete(p->pRight);

  if( p->pList ) sqliteExprListDelete(p->pList);
  if( p->pSelect ) sqliteSelectDelete(p->pSelect);
  sqliteFree(p);
}

/*
** The following group of functions are used to translate the string
................................................................................
        for(j=0; j<pEList->nExpr; j++){
          char *zAs = pEList->a[j].zName;
          if( zAs!=0 && sqliteStrICmp(zAs, z)==0 ){
            cnt++;
            assert( pExpr->pLeft==0 && pExpr->pRight==0 );
            pExpr->op = TK_AS;
            pExpr->iColumn = j;
            pExpr->pLeft = sqliteExprDup(pEList->a[j].pExpr);
          }
        } 
      }
      if( cnt==0 && sqliteIsRowid(z) ){
        pExpr->iColumn = -1;
        pExpr->iTable = base;
        cnt = 1 + (pTabList->nId>1);

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing SELECT statements that contain
# subqueries in their FROM clause.
#
# $Id: select6.test,v 1.5 2002/03/03 03:11:15 drh Exp $

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

do_test select6-1.0 {
  execsql {
    BEGIN;
................................................................................
      (SELECT a.q, a.p, b.r
       FROM (SELECT count(*) as p , b as q FROM t2 GROUP BY q) AS a,
            (SELECT max(a) as r, b as s FROM t2 GROUP BY s) as b
       WHERE a.q=b.s ORDER BY a.q)
    ORDER BY [a.q]
  }
} {1 1 1 2 2 3 3 4 7 4 8 15 5 5 20}

do_test select6-3.3 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1)
  }
} {10.5 3.7 14.2}
do_test select6-3.4 {
  execsql {

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing SELECT statements that contain
# subqueries in their FROM clause.
#
# $Id: select6.test,v 1.6 2002/03/03 03:42:31 drh Exp $

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

do_test select6-1.0 {
  execsql {
    BEGIN;
................................................................................
      (SELECT a.q, a.p, b.r
       FROM (SELECT count(*) as p , b as q FROM t2 GROUP BY q) AS a,
            (SELECT max(a) as r, b as s FROM t2 GROUP BY s) as b
       WHERE a.q=b.s ORDER BY a.q)
    ORDER BY [a.q]
  }
} {1 1 1 2 2 3 3 4 7 4 8 15 5 5 20}

do_test select6-3.3 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1)
  }
} {10.5 3.7 14.2}
do_test select6-3.4 {
  execsql {