SQLite

** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.380 2009/04/06 12:26:58 drh Exp $
*/
#include "sqliteInt.h"

/*
** Trace output macros
*/
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)

  ** well put it first in the join order.  That way, perhaps it can be
  ** referenced by other tables in the join.
  */
  memset(pCost, 0, sizeof(*pCost));
  if( pProbe==0 &&
     findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IN|WO_LT|WO_LE|WO_GT|WO_GE,0)==0 &&
     (pOrderBy==0 || !sortableByRowid(iCur, pOrderBy, pWC->pMaskSet, &rev)) ){
     if( pParse->db->flags & SQLITE_ReverseOrder ){
      /* For application testing, randomly reverse the output order for
      ** SELECT statements that omit the ORDER BY clause.  This will help
      ** to find cases where
      */
      pCost->plan.wsFlags |= WHERE_REVERSE;
    }
    return;
  }
  pCost->rCost = SQLITE_BIG_DBL;

  /* Check for a rowid=EXPR or rowid IN (...) constraints. If there was
  ** an INDEXED BY clause attached to this table, skip this step.
  */

# 2009 February 23
#
# 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 the reverse_select_order pragma.
#
# $Id: whereA.test,v 1.2 2009/04/06 12:26:58 drh Exp $

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

do_test whereA-1.1 {
  db eval {
    CREATE TABLE t1(a INTEGER PRIMARY KEY, b UNIQUE, c);

} {2 hello world 3 4.53 {} 1 2 3}
do_test whereA-3.3 {
  db eval {
    PRAGMA reverse_unordered_selects=1;
    SELECT * FROM t1 WHERE b>0 ORDER BY b;
  }
} {1 2 3 3 4.53 {} 2 hello world}

do_test whereA-4.1 {
  db eval {
    CREATE TABLE t2(x);
    INSERT INTO t2 VALUES(1);
    INSERT INTO t2 VALUES(2);
    SELECT x FROM t2;
  }
} {2 1}


finish_test