SQLite

** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is reponsible 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 1.252 2007/06/08 08:39:02 drh Exp $
** $Id: where.c,v 1.253 2007/06/11 12:56:15 drh Exp $
*/
#include "sqliteInt.h"

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

    pLeft = pExpr->pList->a[1].pExpr;
    pRight = pExpr->pList->a[0].pExpr;
    pStr1 = sqlite3Expr(TK_STRING, 0, 0, 0);
    if( pStr1 ){
      sqlite3TokenCopy(&pStr1->token, &pRight->token);
      pStr1->token.n = nPattern;
      pStr1->flags = EP_Dequoted;
    }
    pStr2 = sqlite3ExprDup(pStr1);
    if( pStr2 ){
      assert( pStr2->token.dyn );
      ++*(u8*)&pStr2->token.z[nPattern-1];
    }
    pNewExpr1 = sqlite3Expr(TK_GE, sqlite3ExprDup(pLeft), pStr1, 0);

#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the LIKE and GLOB operators and
# in particular the optimizations that occur to help those operators
# run faster.
#
# $Id: like.test,v 1.5 2006/06/14 08:48:26 danielk1977 Exp $
# $Id: like.test,v 1.6 2007/06/11 12:56:15 drh Exp $

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

# Create some sample data to work with.
#
do_test like-1.0 {

    SELECT x FROM t2 WHERE x GLOB 'abc*' ORDER BY 1
  }
} {abc abcd nosort {} i2}
do_test like-5.8 {
  set sqlite_like_count
} 12

# ticket #2407

#
# Make sure the LIKE prefix optimization does not strip off leading
# characters of the like pattern that happen to be quote characters.
#
do_test like-6.1 {
  foreach x { 'abc 'bcd 'def 'ax } {
    db eval {INSERT INTO t2 VALUES($x)}
  }
  execsql {
    SELECT * FROM t2 WHERE x LIKE '''a%'
  }
} {'abc 'ax}

finish_test