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 1.343 2007/05/09 22:56:39 drh Exp $
*/
#include "sqliteInt.h"


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

  sqlite3VdbeAddOp(v, OP_Distinct, iTab, sqlite3VdbeCurrentAddr(v)+3);
  sqlite3VdbeAddOp(v, OP_Pop, N+1, 0);
  sqlite3VdbeAddOp(v, OP_Goto, 0, addrRepeat);
  VdbeComment((v, "# skip indistinct records"));
  sqlite3VdbeAddOp(v, OP_IdxInsert, iTab, 0);
}

/*
** Generate an error message when a SELECT is used within a subexpression
** (example:  "a IN (SELECT * FROM table)") but it has more than 1 result
** column.  We do this in a subroutine because the error occurs in multiple
** places.
*/
static int checkForMultiColumnSelectError(Parse *pParse, int eDest, int nExpr){
  if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){
    sqlite3ErrorMsg(pParse, "only a single result allowed for "
       "a SELECT that is part of an expression");
    return 1;
  }else{
    return 0;
  }
}

/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab and nColumn are both zero, then the pEList expressions
** are evaluated in order to get the data for this row.  If nColumn>0

    assert( pEList!=0 );
    assert( pEList->nExpr==nColumn );
    codeDistinct(v, distinct, iContinue, nColumn);
    if( pOrderBy==0 ){
      codeOffset(v, p, iContinue, nColumn);
    }
  }

  if( checkForMultiColumnSelectError(pParse, eDest, pEList->nExpr) ){
    return 0;
  }

  switch( eDest ){
    /* In this mode, write each query result to the key of the temporary
    ** table iParm.
    */
#ifndef SQLITE_OMIT_COMPOUND_SELECT
    case SRT_Union: {

  */
  if( pParse->nErr>0 ) goto select_end;

  /* If writing to memory or generating a set
  ** only a single column may be output.
  */
#ifndef SQLITE_OMIT_SUBQUERY
  if( checkForMultiColumnSelectError(pParse, eDest, pEList->nExpr) ){


    goto select_end;
  }
#endif

  /* ORDER BY is ignored for some destinations.
  */
  if( IgnorableOrderby(eDest) ){

# 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.  The
# focus of this file is testing compute SELECT statements and nested
# views.
#
# $Id: select7.test,v 1.9 2007/05/09 22:56:39 drh Exp $


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

ifcapable compound {

      SELECT P.pk from PHOTO P WHERE NOT EXISTS ( 
           SELECT T2.pk from TAG T2 WHERE T2.fk = P.pk 
           EXCEPT 
           SELECT T3.pk from TAG T3 WHERE T3.fk = P.pk AND T3.name LIKE '%foo%'
      );
    }
  } {2 3}
}

# ticket #2347
#
ifcapable {subquery && compound} {
  do_test select7-5.1 {
    catchsql {
      CREATE TABLE t2(a,b);
      SELECT 5 IN (SELECT a,b FROM t2);
    }
  } [list 1 \
     {only a single result allowed for a SELECT that is part of an expression}]
  do_test select7-5.2 {
    catchsql {
      SELECT 5 IN (SELECT * FROM t2);
    }
  } [list 1 \
     {only a single result allowed for a SELECT that is part of an expression}]
  do_test select7-5.3 {
    catchsql {
      SELECT 5 IN (SELECT a,b FROM t2 UNION SELECT b,a FROM t2);
    }
  } [list 1 \
     {only a single result allowed for a SELECT that is part of an expression}]
  do_test select7-5.4 {
    catchsql {
      SELECT 5 IN (SELECT * FROM t2 UNION SELECT * FROM t2);
    }
  } [list 1 \
     {only a single result allowed for a SELECT that is part of an expression}]
}

finish_test