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 1.328 2008/11/03 09:06:06 danielk1977 Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)

      if( bRev ){
        pTerm = pStart;
        pStart = pEnd;
        pEnd = pTerm;
      }
      if( pStart ){
        Expr *pX;
        int r1;
        pX = pStart->pExpr;
        assert( pX!=0 );
        assert( pStart->leftCursor==iCur );

        /* The ForceInt instruction may modify the register that it operates
        ** on. For example it may replace a real value with an integer one,
        ** or if p3 is true it may increment the register value. For this
        ** reason we need to make sure that register r1 is really a newly
        ** allocated temporary register, and not part of the column-cache.
        ** For this reason we cannot use sqlite3ExprCodeTemp() here.
        */
        r1 = sqlite3GetTempReg(pParse);
        sqlite3ExprCode(pParse, pX->pRight, r1);

        sqlite3VdbeAddOp3(v, OP_ForceInt, r1, brk, 
                             pX->op==TK_LE || pX->op==TK_GT);
        sqlite3VdbeAddOp3(v, bRev ? OP_MoveLt : OP_MoveGe, iCur, brk, r1);
        VdbeComment((v, "pk"));
        sqlite3ReleaseTempReg(pParse, r1);
        disableTerm(pLevel, pStart);
      }else{
        sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, brk);
      }
      if( pEnd ){
        Expr *pX;
        pX = pEnd->pExpr;

# 2001 September 15
#
# 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 use of indices in WHERE clases.
#
# $Id: where.test,v 1.50 2008/11/03 09:06:06 danielk1977 Exp $

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

# Build some test data
#
do_test where-1.0 {

do_test where-16.4 {
  execsql {
    SELECT bar.RowID id FROM foo, bar WHERE foo.idx = bar.RowID AND id = 2;
  }
} {2 2}

integrity_check {where-99.0}

#---------------------------------------------------------------------
# These tests test that a bug surrounding the use of ForceInt has been
# fixed in where.c.
#
do_test where-17.1 {
  execsql {
    CREATE TABLE tbooking (
      id INTEGER PRIMARY KEY,
      eventtype INTEGER NOT NULL
    );
    INSERT INTO tbooking VALUES(42, 3);
    INSERT INTO tbooking VALUES(43, 4);
  }
} {}
do_test where-17.2 {
  execsql {
    SELECT a.id
    FROM tbooking AS a
    WHERE a.eventtype=3;
  }
} {42}
do_test where-17.3 {
  execsql {
    SELECT a.id, (SELECT b.id FROM tbooking AS b WHERE b.id>a.id)
    FROM tbooking AS a
    WHERE a.eventtype=3;
  }
} {42 43}
do_test where-17.4 {
  execsql {
    SELECT a.id, (SELECT b.id FROM tbooking AS b WHERE b.id>a.id)
    FROM (SELECT 1.5 AS id) AS a
  }
} {1.5 42}
do_test where-17.5 {
  execsql {
    CREATE TABLE tother(a, b);
    INSERT INTO tother VALUES(1, 3.7);
    SELECT id, a FROM tbooking, tother WHERE id>a;
  }
} {42 1 43 1}

finish_test