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 1.323 2008/10/01 08:43:03 danielk1977 Exp $
*/
#include "sqliteInt.h"

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

  WhereLevel *pLevel, /* When level of the FROM clause we are working on */
  int iTarget         /* Attempt to leave results in this register */
){
  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( iTarget>0 );


  if( pX->op==TK_EQ ){
    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{

    if( pLevel->flags & WHERE_ROWID_EQ ){
      /* Case 1:  We can directly reference a single row using an
      **          equality comparison against the ROWID field.  Or
      **          we reference multiple rows using a "rowid IN (...)"
      **          construct.
      */
      int r1;
      int rtmp = sqlite3GetTempReg(pParse);
      pTerm = findTerm(&wc, iCur, -1, notReady, WO_EQ|WO_IN, 0);
      assert( pTerm!=0 );
      assert( pTerm->pExpr!=0 );
      assert( pTerm->leftCursor==iCur );
      assert( omitTable==0 );
      r1 = codeEqualityTerm(pParse, pTerm, pLevel, rtmp);
      nxt = pLevel->nxt;
      sqlite3VdbeAddOp2(v, OP_MustBeInt, r1, nxt);
      sqlite3VdbeAddOp3(v, OP_NotExists, iCur, nxt, r1);
      sqlite3ReleaseTempReg(pParse, rtmp);
      VdbeComment((v, "pk"));
      pLevel->op = OP_Noop;
    }else if( pLevel->flags & WHERE_ROWID_RANGE ){
      /* Case 2:  We have an inequality comparison against the ROWID field.
      */
      int testOp = OP_Noop;
      int start;

# 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 1.48 2008/10/01 08:43:03 danielk1977 Exp $

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

# Build some test data
#
do_test where-1.0 {

do_test where-15.1 {
  execsql {
    CREATE TEMP TABLE t1 (a, b, c, d, e);
    CREATE TEMP TABLE t2 (f);
    SELECT t1.e AS alias FROM t2, t1 WHERE alias = 1 ;
  }
} {}

# Ticket #3408.
# 
# The branch of code in where.c that generated rowid lookups was
# incorrectly deallocating a constant register, meaning that if the 
# vdbe code ran more than once, the second time around the constant
# value may have been clobbered by some other value.
# 
do_test where-16.1 {
  execsql {
    CREATE TABLE a1(id INTEGER PRIMARY KEY, v);
    CREATE TABLE a2(id INTEGER PRIMARY KEY, v);
    INSERT INTO a1 VALUES(1, 'one');
    INSERT INTO a1 VALUES(2, 'two');
    INSERT INTO a2 VALUES(1, 'one');
    INSERT INTO a2 VALUES(2, 'two');
  }
} {}
do_test where-16.2 {
  execsql {
    SELECT * FROM a2 CROSS JOIN a1 WHERE a1.id=1 AND a1.v='one';
  }
} {1 one 1 one 2 two 1 one}

# The actual problem reported in #3408.
do_test where-16.3 {
  execsql {
    CREATE TEMP TABLE foo(idx INTEGER);
    INSERT INTO foo VALUES(1);
    INSERT INTO foo VALUES(1);
    INSERT INTO foo VALUES(1);
    INSERT INTO foo VALUES(2);
    INSERT INTO foo VALUES(2);
    CREATE TEMP TABLE bar(stuff INTEGER);
    INSERT INTO bar VALUES(100);
    INSERT INTO bar VALUES(200);
    INSERT INTO bar VALUES(300);
  }
} {}
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}

finish_test