SQLite

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.50 2002/06/09 01:55:20 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.

    **
    ** The IN operator as in "<expr> IN (...)" is treated the same as
    ** an equality comparison.
    */
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      int eqMask = 0;  /* Index columns covered by an x=... constraint */
      int ltMask = 0;  /* Index columns covered by an x<... constraint */
      int gtMask = 0;  /* Index columns covered by an x>... constraint */
      int inMask = 0;  /* Index columns covered by an x IN .. constraint */
      int nEq, m, score;

      if( pIdx->isDropped ) continue;   /* Ignore dropped indices */
      if( pIdx->nColumn>32 ) continue;  /* Ignore indices too many columns */
      for(j=0; j<nExpr; j++){
        if( aExpr[j].idxLeft==idx 
             && (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
          int iColumn = aExpr[j].p->pLeft->iColumn;
          int k;
          for(k=0; k<pIdx->nColumn; k++){
            if( pIdx->aiColumn[k]==iColumn ){
              switch( aExpr[j].p->op ){
                case TK_IN: {
                  if( k==0 ) inMask |= 1;
                  break;
                }
                case TK_EQ: {
                  eqMask |= 1<<k;
                  break;
                }
                case TK_LE:
                case TK_LT: {
                  ltMask |= 1<<k;

        m = (1<<(nEq+1))-1;
        if( (m & eqMask)!=m ) break;
      }
      score = nEq*4;
      m = 1<<nEq;
      if( m & ltMask ) score++;
      if( m & gtMask ) score+=2;
      if( score==0 && inMask ) score = 4;
      if( score>bestScore ){
        pBestIdx = pIdx;
        bestScore = score;
      }
    }
    pWInfo->a[i].pIdx = pBestIdx;
    pWInfo->a[i].score = bestScore;

# 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 1.7 2002/06/09 01:55:20 drh Exp $

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

# Build some test data
#
do_test where-1.0 {

  }
} {}
do_test where-4.4 {
  execsql {
    SELECT 99 WHERE 1
  }
} {99}

# Verify that IN operators in a WHERE clause are handled correctly.
#
do_test where-5.1 {
  count {
    SELECT * FROM t1 WHERE rowid IN (1,2,3,1234) order by 1;
  }
} {1 0 4 2 1 9 3 1 16 0}
do_test where-5.2 {
  count {
    SELECT * FROM t1 WHERE rowid+0 IN (1,2,3,1234) order by 1;
  }
} {1 0 4 2 1 9 3 1 16 99}
do_test where-5.3 {
  count {
    SELECT * FROM t1 WHERE w IN (-1,1,2,3) order by 1;
  }
} {1 0 4 2 1 9 3 1 16 10}
do_test where-5.4 {
  count {
    SELECT * FROM t1 WHERE w+0 IN (-1,1,2,3) order by 1;
  }
} {1 0 4 2 1 9 3 1 16 99}
do_test where-5.5 {
  count {
    SELECT * FROM t1 WHERE rowid IN 
       (select rowid from t1 where rowid IN (-1,2,4))
    ORDER BY 1;
  }
} {2 1 9 4 2 25 1}
do_test where-5.6 {
  count {
    SELECT * FROM t1 WHERE rowid+0 IN 
       (select rowid from t1 where rowid IN (-1,2,4))
    ORDER BY 1;
  }
} {2 1 9 4 2 25 99}
do_test where-5.7 {
  count {
    SELECT * FROM t1 WHERE w IN 
       (select rowid from t1 where rowid IN (-1,2,4))
    ORDER BY 1;
  }
} {2 1 9 4 2 25 7}
do_test where-5.8 {
  count {
    SELECT * FROM t1 WHERE w+0 IN 
       (select rowid from t1 where rowid IN (-1,2,4))
    ORDER BY 1;
  }
} {2 1 9 4 2 25 99}
do_test where-5.9 {
  count {
    SELECT * FROM t1 WHERE x IN (1,7) ORDER BY 1;
  }
} {2 1 9 3 1 16 6}
do_test where-5.10 {
  count {
    SELECT * FROM t1 WHERE x+0 IN (1,7) ORDER BY 1;
  }
} {2 1 9 3 1 16 99}
do_test where-5.11 {
  count {
    SELECT * FROM t1 WHERE y IN (6400,8100) ORDER BY 1;
  }
} {79 6 6400 89 6 8100 99}
do_test where-5.12 {
  count {
    SELECT * FROM t1 WHERE x=6 AND y IN (6400,8100) ORDER BY 1;
  }
} {79 6 6400 89 6 8100 74}
do_test where-5.13 {
  count {
    SELECT * FROM t1 WHERE x IN (1,7) AND y NOT IN (6400,8100) ORDER BY 1;
  }
} {2 1 9 3 1 16 6}
do_test where-5.14 {
  count {
    SELECT * FROM t1 WHERE x IN (1,7) AND y IN (9,10) ORDER BY 1;
  }
} {2 1 9 6}



finish_test