**    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 1.317 2006/06/20 13:07:27 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
................................................................................
      assert( pExpr->pLeft==0 );
      pExpr->pLeft = sqlite3ExprDup(pNew->pLeft);
      assert( pExpr->pRight==0 );
      pExpr->pRight = sqlite3ExprDup(pNew->pRight);
      assert( pExpr->pList==0 );
      pExpr->pList = sqlite3ExprListDup(pNew->pList);
      pExpr->iTable = pNew->iTable;

      pExpr->iColumn = pNew->iColumn;
      pExpr->iAgg = pNew->iAgg;
      sqlite3TokenCopy(&pExpr->token, &pNew->token);
      sqlite3TokenCopy(&pExpr->span, &pNew->span);
      pExpr->pSelect = sqlite3SelectDup(pNew->pSelect);
      pExpr->flags = pNew->flags;
    }

**    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 1.318 2006/06/21 07:02:33 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
................................................................................
      assert( pExpr->pLeft==0 );
      pExpr->pLeft = sqlite3ExprDup(pNew->pLeft);
      assert( pExpr->pRight==0 );
      pExpr->pRight = sqlite3ExprDup(pNew->pRight);
      assert( pExpr->pList==0 );
      pExpr->pList = sqlite3ExprListDup(pNew->pList);
      pExpr->iTable = pNew->iTable;
      pExpr->pTab = pNew->pTab;
      pExpr->iColumn = pNew->iColumn;
      pExpr->iAgg = pNew->iAgg;
      sqlite3TokenCopy(&pExpr->token, &pNew->token);
      sqlite3TokenCopy(&pExpr->span, &pNew->span);
      pExpr->pSelect = sqlite3SelectDup(pNew->pSelect);
      pExpr->flags = pNew->flags;
    }

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the virtual table interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test8.c,v 1.27 2006/06/20 11:01:08 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................

static int echoColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  int iCol = i + 1;
  sqlite3_stmt *pStmt = ((echo_cursor *)cur)->pStmt;
  if( ((echo_cursor *)cur)->errcode ){
    return ((echo_cursor *)cur)->errcode;
  }




  assert( sqlite3_data_count(pStmt)>iCol );
  sqlite3_result_value(ctx, sqlite3_column_value(pStmt, iCol));

  return SQLITE_OK;
}

static int echoRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  sqlite3_stmt *pStmt = ((echo_cursor *)cur)->pStmt;
  *pRowid = sqlite3_column_int64(pStmt, 0);
  return SQLITE_OK;
................................................................................
  echo_vtab *pVtab = (echo_vtab *)pVtabCursor->pVtab;
  sqlite3 *db = pVtab->db;

  assert( idxNum==hashString(idxStr) );
  sqlite3_finalize(pCur->pStmt);
  pCur->pStmt = 0;
  rc = sqlite3_prepare(db, idxStr, -1, &pCur->pStmt, 0);

  for(i=0; rc==SQLITE_OK && i<argc; i++){
    switch( sqlite3_value_type(argv[i]) ){
      case SQLITE_INTEGER: {
        sqlite3_bind_int64(pCur->pStmt, i+1, sqlite3_value_int64(argv[i]));
        break;
      }
      case SQLITE_FLOAT: {

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the virtual table interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test8.c,v 1.28 2006/06/21 07:02:34 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................

static int echoColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  int iCol = i + 1;
  sqlite3_stmt *pStmt = ((echo_cursor *)cur)->pStmt;
  if( ((echo_cursor *)cur)->errcode ){
    return ((echo_cursor *)cur)->errcode;
  }

  if( !pStmt ){
    sqlite3_result_null(ctx);
  }else{
    assert( sqlite3_data_count(pStmt)>iCol );
    sqlite3_result_value(ctx, sqlite3_column_value(pStmt, iCol));
  }
  return SQLITE_OK;
}

static int echoRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  sqlite3_stmt *pStmt = ((echo_cursor *)cur)->pStmt;
  *pRowid = sqlite3_column_int64(pStmt, 0);
  return SQLITE_OK;
................................................................................
  echo_vtab *pVtab = (echo_vtab *)pVtabCursor->pVtab;
  sqlite3 *db = pVtab->db;

  assert( idxNum==hashString(idxStr) );
  sqlite3_finalize(pCur->pStmt);
  pCur->pStmt = 0;
  rc = sqlite3_prepare(db, idxStr, -1, &pCur->pStmt, 0);
  assert( pCur->pStmt || rc!=SQLITE_OK );
  for(i=0; rc==SQLITE_OK && i<argc; i++){
    switch( sqlite3_value_type(argv[i]) ){
      case SQLITE_INTEGER: {
        sqlite3_bind_int64(pCur->pStmt, i+1, sqlite3_value_int64(argv[i]));
        break;
      }
      case SQLITE_FLOAT: {

#    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.  The
# focus of this file is creating and dropping virtual tables.
#
# $Id: vtab1.test,v 1.24 2006/06/20 13:07:28 danielk1977 Exp $

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

ifcapable !vtab||!schema_pragmas {
  finish_test
  return
................................................................................
  }
} {1 2 3 4 5 6}
do_test vtab1-3.7 {
  execsql {
    SELECT rowid, * FROM t1;
  }
} {1 1 2 3 2 4 5 6}






# Execute some SELECT statements with WHERE clauses on the t1 table.
# Then check the echo_module variable (written to by the module methods
# in test8.c) to make sure the xBestIndex() and xFilter() methods were
# called correctly.
#
do_test vtab1-3.8 {

#    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.  The
# focus of this file is creating and dropping virtual tables.
#
# $Id: vtab1.test,v 1.25 2006/06/21 07:02:34 danielk1977 Exp $

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

ifcapable !vtab||!schema_pragmas {
  finish_test
  return
................................................................................
  }
} {1 2 3 4 5 6}
do_test vtab1-3.7 {
  execsql {
    SELECT rowid, * FROM t1;
  }
} {1 1 2 3 2 4 5 6}
do_test vtab1-3.8 {
  execsql {
    SELECT a AS d, b AS e, c AS f FROM t1;
  }
} {1 2 3 4 5 6}

# Execute some SELECT statements with WHERE clauses on the t1 table.
# Then check the echo_module variable (written to by the module methods
# in test8.c) to make sure the xBestIndex() and xFilter() methods were
# called correctly.
#
do_test vtab1-3.8 {

# 2002 May 24
#
# 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.
#
# This file implements tests for joins, including outer joins involving
# virtual tables. The test cases in this file are copied from the file
# join.test, and some of the comments still reflect that.
#
# $Id: vtab6.test,v 1.1 2006/06/21 07:02:34 danielk1977 Exp $

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

register_echo_module [sqlite3_connection_pointer db]

execsql {
  CREATE TABLE real_t1(a,b,c);
  CREATE TABLE real_t2(b,c,d);
  CREATE TABLE real_t3(c,d,e);
  CREATE TABLE real_t4(d,e,f);
  CREATE TABLE real_t5(a INTEGER PRIMARY KEY);
  CREATE TABLE real_t6(a INTEGER);
  CREATE TABLE real_t7 (x, y);
  CREATE TABLE real_t8 (a integer primary key, b);
  CREATE TABLE real_t9(a INTEGER PRIMARY KEY, b);
  CREATE TABLE real_t10(x INTEGER PRIMARY KEY, y);
  CREATE TABLE real_t11(p INTEGER PRIMARY KEY, q);
  CREATE TABLE real_t12(a,b);
  CREATE TABLE real_t13(b,c);
  CREATE TABLE real_t21(a,b,c);
  CREATE TABLE real_t22(p,q);
}
foreach t [list t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 t21 t22] {
  execsql "CREATE VIRTUAL TABLE $t USING echo(real_$t)"
}

do_test vtab6-1.1 {
  execsql {
    INSERT INTO t1 VALUES(1,2,3);
    INSERT INTO t1 VALUES(2,3,4);
    INSERT INTO t1 VALUES(3,4,5);
    SELECT * FROM t1;
  }  
} {1 2 3 2 3 4 3 4 5}
do_test vtab6-1.2 {
  execsql {
    INSERT INTO t2 VALUES(1,2,3);
    INSERT INTO t2 VALUES(2,3,4);
    INSERT INTO t2 VALUES(3,4,5);
    SELECT * FROM t2;
  }  
} {1 2 3 2 3 4 3 4 5}

do_test vtab6-1.3 {
  execsql2 {
    SELECT * FROM t1 NATURAL JOIN t2;
  }
} {a 1 b 2 c 3 d 4 a 2 b 3 c 4 d 5}
do_test vtab6-1.3.1 {
  execsql2 {
    SELECT * FROM t2 NATURAL JOIN t1;
  }
} {b 2 c 3 d 4 a 1 b 3 c 4 d 5 a 2}
do_test vtab6-1.3.2 {
  execsql2 {
    SELECT * FROM t2 AS x NATURAL JOIN t1;
  }
} {b 2 c 3 d 4 a 1 b 3 c 4 d 5 a 2}
do_test vtab6-1.3.3 {
  execsql2 {
    SELECT * FROM t2 NATURAL JOIN t1 AS y;
  }
} {b 2 c 3 d 4 a 1 b 3 c 4 d 5 a 2}
do_test vtab6-1.3.4 {
  execsql {
    SELECT b FROM t1 NATURAL JOIN t2;
  }
} {2 3}
do_test vtab6-1.4.1 {
  execsql2 {
    SELECT * FROM t1 INNER JOIN t2 USING(b,c);
  }
} {a 1 b 2 c 3 d 4 a 2 b 3 c 4 d 5}
do_test vtab6-1.4.2 {
  execsql2 {
    SELECT * FROM t1 AS x INNER JOIN t2 USING(b,c);
  }
} {a 1 b 2 c 3 d 4 a 2 b 3 c 4 d 5}
do_test vtab6-1.4.3 {
  execsql2 {
    SELECT * FROM t1 INNER JOIN t2 AS y USING(b,c);
  }
} {a 1 b 2 c 3 d 4 a 2 b 3 c 4 d 5}
do_test vtab6-1.4.4 {
  execsql2 {
    SELECT * FROM t1 AS x INNER JOIN t2 AS y USING(b,c);
  }
} {a 1 b 2 c 3 d 4 a 2 b 3 c 4 d 5}
do_test vtab6-1.4.5 {
  execsql {
    SELECT b FROM t1 JOIN t2 USING(b);
  }
} {2 3}
do_test vtab6-1.5 {
  execsql2 {
    SELECT * FROM t1 INNER JOIN t2 USING(b);
  }
} {a 1 b 2 c 3 c 3 d 4 a 2 b 3 c 4 c 4 d 5}
do_test vtab6-1.6 {
  execsql2 {
    SELECT * FROM t1 INNER JOIN t2 USING(c);
  }
} {a 1 b 2 c 3 b 2 d 4 a 2 b 3 c 4 b 3 d 5}
do_test vtab6-1.7 {
  execsql2 {
    SELECT * FROM t1 INNER JOIN t2 USING(c,b);
  }
} {a 1 b 2 c 3 d 4 a 2 b 3 c 4 d 5}

do_test vtab6-1.8 {
  execsql {
    SELECT * FROM t1 NATURAL CROSS JOIN t2;
  }
} {1 2 3 4 2 3 4 5}
do_test vtab6-1.9 {
  execsql {
    SELECT * FROM t1 CROSS JOIN t2 USING(b,c);
  }
} {1 2 3 4 2 3 4 5}
do_test vtab6-1.10 {
  execsql {
    SELECT * FROM t1 NATURAL INNER JOIN t2;
  }
} {1 2 3 4 2 3 4 5}
do_test vtab6-1.11 {
  execsql {
    SELECT * FROM t1 INNER JOIN t2 USING(b,c);
  }
} {1 2 3 4 2 3 4 5}
do_test vtab6-1.12 {
  execsql {
    SELECT * FROM t1 natural inner join t2;
  }
} {1 2 3 4 2 3 4 5}

ifcapable subquery {
breakpoint
  do_test vtab6-1.13 {
    execsql2 {
      SELECT * FROM t1 NATURAL JOIN 
        (SELECT b as 'c', c as 'd', d as 'e' FROM t2) as t3
    }
  } {a 1 b 2 c 3 d 4 e 5}
  do_test vtab6-1.14 {
    execsql2 {
      SELECT * FROM (SELECT b as 'c', c as 'd', d as 'e' FROM t2) as 'tx'
          NATURAL JOIN t1
    }
  } {c 3 d 4 e 5 a 1 b 2}
}

do_test vtab6-1.15 {
  execsql {
    INSERT INTO t3 VALUES(2,3,4);
    INSERT INTO t3 VALUES(3,4,5);
    INSERT INTO t3 VALUES(4,5,6);
    SELECT * FROM t3;
  }  
} {2 3 4 3 4 5 4 5 6}
do_test vtab6-1.16 {
  execsql {
    SELECT * FROM t1 natural join t2 natural join t3;
  }
} {1 2 3 4 5 2 3 4 5 6}
do_test vtab6-1.17 {
  execsql2 {
    SELECT * FROM t1 natural join t2 natural join t3;
  }
} {a 1 b 2 c 3 d 4 e 5 a 2 b 3 c 4 d 5 e 6}
do_test vtab6-1.18 {
  execsql {
    INSERT INTO t4 VALUES(2,3,4);
    INSERT INTO t4 VALUES(3,4,5);
    INSERT INTO t4 VALUES(4,5,6);
    SELECT * FROM t4;
  }  
} {2 3 4 3 4 5 4 5 6}
do_test vtab6-1.19.1 {
  execsql {
    SELECT * FROM t1 natural join t2 natural join t4;
  }
} {1 2 3 4 5 6}
do_test vtab6-1.19.2 {
  execsql2 {
    SELECT * FROM t1 natural join t2 natural join t4;
  }
} {a 1 b 2 c 3 d 4 e 5 f 6}
do_test vtab6-1.20 {
  execsql {
    SELECT * FROM t1 natural join t2 natural join t3 WHERE t1.a=1
  }
} {1 2 3 4 5}

do_test vtab6-2.1 {
  execsql {
    SELECT * FROM t1 NATURAL LEFT JOIN t2;
  }
} {1 2 3 4 2 3 4 5 3 4 5 {}}
do_test vtab6-2.2 {
  execsql {
    SELECT * FROM t2 NATURAL LEFT OUTER JOIN t1;
  }
} {1 2 3 {} 2 3 4 1 3 4 5 2}
do_test vtab6-2.3 {
  catchsql {
    SELECT * FROM t1 NATURAL RIGHT OUTER JOIN t2;
  }
} {1 {RIGHT and FULL OUTER JOINs are not currently supported}}
do_test vtab6-2.4 {
  execsql {
    SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.d
  }
} {1 2 3 {} {} {} 2 3 4 {} {} {} 3 4 5 1 2 3}
do_test vtab6-2.5 {
  execsql {
    SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.d WHERE t1.a>1
  }
} {2 3 4 {} {} {} 3 4 5 1 2 3}
do_test vtab6-2.6 {
  execsql {
    SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.d WHERE t2.b IS NULL OR t2.b>1
  }
} {1 2 3 {} {} {} 2 3 4 {} {} {}}

do_test vtab6-3.1 {
  catchsql {
    SELECT * FROM t1 NATURAL JOIN t2 ON t1.a=t2.b;
  }
} {1 {a NATURAL join may not have an ON or USING clause}}
do_test vtab6-3.2 {
  catchsql {
    SELECT * FROM t1 NATURAL JOIN t2 USING(b);
  }
} {1 {a NATURAL join may not have an ON or USING clause}}
do_test vtab6-3.3 {
  catchsql {
    SELECT * FROM t1 JOIN t2 ON t1.a=t2.b USING(b);
  }
} {1 {cannot have both ON and USING clauses in the same join}}
do_test vtab6-3.4 {
  catchsql {
    SELECT * FROM t1 JOIN t2 USING(a);
  }
} {1 {cannot join using column a - column not present in both tables}}
do_test vtab6-3.5 {
  catchsql {
    SELECT * FROM t1 USING(a);
  }
} {0 {1 2 3 2 3 4 3 4 5}}
do_test vtab6-3.6 {
  catchsql {
    SELECT * FROM t1 JOIN t2 ON t3.a=t2.b;
  }
} {1 {no such column: t3.a}}
do_test vtab6-3.7 {
  catchsql {
    SELECT * FROM t1 INNER OUTER JOIN t2;
  }
} {1 {unknown or unsupported join type: INNER OUTER}}
do_test vtab6-3.7 {
  catchsql {
    SELECT * FROM t1 LEFT BOGUS JOIN t2;
  }
} {1 {unknown or unsupported join type: LEFT BOGUS}}

do_test vtab6-4.1 {
  execsql {
    BEGIN;
    INSERT INTO t6 VALUES(NULL);
    INSERT INTO t6 VALUES(NULL);
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    COMMIT;
  }
  execsql {
    SELECT * FROM t6 NATURAL JOIN t5;
  }
} {}
do_test vtab6-4.2 {
  execsql {
    SELECT * FROM t6, t5 WHERE t6.a<t5.a;
  }
} {}
do_test vtab6-4.3 {
  execsql {
    SELECT * FROM t6, t5 WHERE t6.a>t5.a;
  }
} {}
do_test vtab6-4.4 {
  execsql {
    UPDATE t6 SET a='xyz';
    SELECT * FROM t6 NATURAL JOIN t5;
  }
} {}
do_test vtab6-4.6 {
  execsql {
    SELECT * FROM t6, t5 WHERE t6.a<t5.a;
  }
} {}
do_test vtab6-4.7 {
  execsql {
    SELECT * FROM t6, t5 WHERE t6.a>t5.a;
  }
} {}
do_test vtab6-4.8 {
  execsql {
    UPDATE t6 SET a=1;
    SELECT * FROM t6 NATURAL JOIN t5;
  }
} {}
do_test vtab6-4.9 {
  execsql {
    SELECT * FROM t6, t5 WHERE t6.a<t5.a;
  }
} {}
do_test vtab6-4.10 {
  execsql {
    SELECT * FROM t6, t5 WHERE t6.a>t5.a;
  }
} {}

# A test for ticket #247.
#
do_test vtab6-7.1 {
  execsql {
    INSERT INTO t7 VALUES ("pa1", 1);
    INSERT INTO t7 VALUES ("pa2", NULL);
    INSERT INTO t7 VALUES ("pa3", NULL);
    INSERT INTO t7 VALUES ("pa4", 2);
    INSERT INTO t7 VALUES ("pa30", 131);
    INSERT INTO t7 VALUES ("pa31", 130);
    INSERT INTO t7 VALUES ("pa28", NULL);

    INSERT INTO t8 VALUES (1, "pa1");
    INSERT INTO t8 VALUES (2, "pa4");
    INSERT INTO t8 VALUES (3, NULL);
    INSERT INTO t8 VALUES (4, NULL);
    INSERT INTO t8 VALUES (130, "pa31");
    INSERT INTO t8 VALUES (131, "pa30");

    SELECT coalesce(t8.a,999) from t7 LEFT JOIN t8 on y=a;
  }
} {1 999 999 2 131 130 999}

# Make sure a left join where the right table is really a view that
# is itself a join works right.  Ticket #306.
#
ifcapable view {
do_test vtab6-8.1 {
  execsql {
    BEGIN;
    INSERT INTO t9 VALUES(1,11);
    INSERT INTO t9 VALUES(2,22);
    INSERT INTO t10 VALUES(1,2);
    INSERT INTO t10 VALUES(3,3);    
    INSERT INTO t11 VALUES(2,111);
    INSERT INTO t11 VALUES(3,333);    
    CREATE VIEW v10_11 AS SELECT x, q FROM t10, t11 WHERE t10.y=t11.p;
    COMMIT;
    SELECT * FROM t9 LEFT JOIN v10_11 ON( a=x );
  }
} {1 11 1 111 2 22 {} {}}
ifcapable subquery {
  do_test vtab6-8.2 {
    execsql {
      SELECT * FROM t9 LEFT JOIN (SELECT x, q FROM t10, t11 WHERE t10.y=t11.p)
           ON( a=x);
    }
  } {1 11 1 111 2 22 {} {}}
}
do_test vtab6-8.3 {
  execsql {
    SELECT * FROM v10_11 LEFT JOIN t9 ON( a=x );
  }
} {1 111 1 11 3 333 {} {}}
} ;# ifcapable view

# Ticket #350 describes a scenario where LEFT OUTER JOIN does not
# function correctly if the right table in the join is really
# subquery.
#
# To test the problem, we generate the same LEFT OUTER JOIN in two
# separate selects but with on using a subquery and the other calling
# the table directly.  Then connect the two SELECTs using an EXCEPT.
# Both queries should generate the same results so the answer should
# be an empty set.
#
ifcapable compound {
do_test vtab6-9.1 {
  execsql {
    BEGIN;
    INSERT INTO t12 VALUES(1,11);
    INSERT INTO t12 VALUES(2,22);
    INSERT INTO t13 VALUES(22,222);
    COMMIT;
  }
} {}

ifcapable subquery {
  do_test vtab6-9.1.1 {
    execsql {
      SELECT * FROM t12 NATURAL LEFT JOIN t13
      EXCEPT
      SELECT * FROM t12 NATURAL LEFT JOIN (SELECT * FROM t13 WHERE b>0);
    }
  } {}
}
ifcapable view {
  do_test vtab6-9.2 {
    execsql {
      CREATE VIEW v13 AS SELECT * FROM t13 WHERE b>0;
      SELECT * FROM t12 NATURAL LEFT JOIN t13
        EXCEPT
        SELECT * FROM t12 NATURAL LEFT JOIN v13;
    }
  } {}
} ;# ifcapable view
} ;# ifcapable compound

ifcapable subquery {
do_test vtab6-10.1 {
  execsql {
    CREATE INDEX i22 ON real_t22(q);
    SELECT a FROM t21 LEFT JOIN t22 ON b=p WHERE q=
       (SELECT max(m.q) FROM t22 m JOIN t21 n ON n.b=m.p WHERE n.c=1);
  }  
} {}
} ;# ifcapable subquery

finish_test