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 1.471 2008/08/26 12:56:14 drh Exp $
*/
#include "sqliteInt.h"


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

**        The parent and sub-query may contain WHERE clauses. Subject to
**        rules (11), (13) and (14), they may also contain ORDER BY,
**        LIMIT and OFFSET clauses.
**
**  (18)  If the sub-query is a compound select, then all terms of the
**        ORDER by clause of the parent must be simple references to 
**        columns of the sub-query.
**
**  (19)  The subquery does not use LIMIT or the outer query does not
**        have a WHERE clause.
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.

  if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){
     return 0;         /* Restriction (6)  */
  }
  if( p->pOrderBy && pSub->pOrderBy ){
     return 0;                                           /* Restriction (11) */
  }
  if( isAgg && pSub->pOrderBy ) return 0;                /* Restriction (16) */
  if( pSub->pLimit && p->pWhere ) return 0;              /* Restriction (19) */

  /* OBSOLETE COMMENT 1:
  ** Restriction 3:  If the subquery is a join, make sure the subquery is 
  ** not used as the right operand of an outer join.  Examples of why this
  ** is not allowed:
  **
  **         t1 LEFT OUTER JOIN (t2 JOIN t3)

# 2008 August 26
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file implements regression tests for SQLite library. 
# Specifically, it tests that bug #3334 has been fixed by the
# addition of restriction (19) to the subquery flattener optimization.
#
# $Id: tkt3334.test,v 1.1 2008/08/26 12:56:14 drh Exp $


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

do_test tkt3334-1.0 {
  execsql {
    CREATE TABLE t1(a,b);
    INSERT INTO t1 VALUES(1,934);
    INSERT INTO t1 VALUES(2,221);
    INSERT INTO t1 VALUES(1,372);
    INSERT INTO t1 VALUES(3,552);
    INSERT INTO t1 VALUES(1,719);
    INSERT INTO t1 VALUES(4,102);
    SELECT * FROM t1 ORDER BY b;
  }
} {4 102 2 221 1 372 3 552 1 719 1 934}

do_test tkt3334-1.1 {
  execsql {
    SELECT a FROM (SELECT a FROM t1 ORDER BY b LIMIT 2) WHERE a=1;
  }
} {}
do_test tkt3334-1.2 {
  execsql {
    SELECT count(*) FROM (SELECT a FROM t1 ORDER BY b LIMIT 2) WHERE a=1;
  }
} {0}
do_test tkt3334-1.3 {
  execsql {
    SELECT a FROM (SELECT a FROM t1 ORDER BY b LIMIT 3) WHERE a=1;
  }
} {1}
do_test tkt3334-1.4 {
  execsql {
    SELECT count(*) FROM (SELECT a FROM t1 ORDER BY b LIMIT 3) WHERE a=1;
  }
} {1}
do_test tkt3334-1.5 {
  execsql {
    SELECT a FROM (SELECT a FROM t1 ORDER BY b LIMIT 99) WHERE a=1;
  }
} {1 1 1}
do_test tkt3334-1.6 {
  execsql {
    SELECT count(*) FROM (SELECT a FROM t1 ORDER BY b LIMIT 99) WHERE a=1;
  }
} {3}
do_test tkt3334-1.7 {
  execsql {
    SELECT a FROM (SELECT a FROM t1 ORDER BY b) WHERE a=1;
  }
} {1 1 1}
do_test tkt3334-1.8 {
  execsql {
    SELECT count(*) FROM (SELECT a FROM t1 ORDER BY b) WHERE a=1;
  }
} {3}
do_test tkt3334-1.9 {
  execsql {
    SELECT a FROM (SELECT a FROM t1) WHERE a=1;
  }
} {1 1 1}
do_test tkt3334-1.10 {
  execsql {
    SELECT count(*) FROM (SELECT a FROM t1) WHERE a=1;
  }
} {3}