SQLite

2.4.6

**    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 1.40 2002/04/02 13:26:11 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.
*/
typedef struct ExprInfo ExprInfo;
struct ExprInfo {
  Expr *p;                /* Pointer to the subexpression */
  int indexable;          /* True if this subexprssion is usable by an index */
  int idxLeft;            /* p->pLeft is a column in this table number. -1 if
                          ** p->pLeft is not the column of any table */
  int idxRight;           /* p->pRight is a column in this table number. -1 if
                          ** p->pRight is not the column of any table */
  unsigned prereqLeft;    /* Tables referenced by p->pLeft */
  unsigned prereqRight;   /* Tables referenced by p->pRight */
  unsigned prereqAll;     /* Tables referenced by this expression in any way */
};

/*
** Determine the number of elements in an array.
*/
#define ARRAYSIZE(X)  (sizeof(X)/sizeof(X[0]))

** "base" is the cursor number (the value of the iTable field) that
** corresponds to the first entry in the table list.
*/
static void exprAnalyze(int base, ExprInfo *pInfo){
  Expr *pExpr = pInfo->p;
  pInfo->prereqLeft = exprTableUsage(base, pExpr->pLeft);
  pInfo->prereqRight = exprTableUsage(base, pExpr->pRight);
  pInfo->prereqAll = exprTableUsage(base, pExpr);
  pInfo->indexable = 0;
  pInfo->idxLeft = -1;
  pInfo->idxRight = -1;
  if( allowedOp(pExpr->op) && (pInfo->prereqRight & pInfo->prereqLeft)==0 ){
    if( pExpr->pRight->op==TK_COLUMN ){
      pInfo->idxRight = pExpr->pRight->iTable - base;
      pInfo->indexable = 1;

    loopMask |= 1<<idx;

    /* Insert code to test every subexpression that can be completely
    ** computed using the current set of tables.
    */
    for(j=0; j<nExpr; j++){
      if( aExpr[j].p==0 ) continue;

      if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
      if( haveKey ){
        haveKey = 0;
        sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0);
      }
      sqliteExprIfFalse(pParse, aExpr[j].p, cont);
      aExpr[j].p = 0;
    }

# 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 SELECT statement.
#
# $Id: select2.test,v 1.18 2002/04/02 13:26:11 drh Exp $

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

# Create a table with some data
#
execsql {CREATE TABLE tbl1(f1 int, f2 int)}

    INSERT INTO aa VALUES(1);
    INSERT INTO aa VALUES(3);
    INSERT INTO bb VALUES(2);
    INSERT INTO bb VALUES(4);
    SELECT * FROM aa, bb WHERE max(a,b)>2;
  }
} {1 4 3 2 3 4}
do_test select2-4.2 {
  execsql {
    INSERT INTO bb VALUES(0);
    SELECT * FROM aa, bb WHERE b;
  }
} {1 2 1 4 3 2 3 4}
do_test select2-4.3 {
  execsql {
    SELECT * FROM aa, bb WHERE NOT b;
  }
} {1 0 3 0}
do_test select2-4.4 {
  execsql {
    SELECT * FROM aa, bb WHERE min(a,b);
  }
} {1 2 1 4 3 2 3 4}
do_test select2-4.5 {
  execsql {
    SELECT * FROM aa, bb WHERE NOT min(a,b);
  }
} {1 0 3 0}
do_test select2-4.6 {
  execsql {
    SELECT * FROM aa, bb WHERE CASE WHEN a=b-1 THEN 1 END;
  }
} {1 2 3 4}
do_test select2-4.7 {
  execsql {
    SELECT * FROM aa, bb WHERE CASE WHEN a=b-1 THEN 0 ELSE 1 END;
  }
} {1 4 1 0 3 2 3 0}

finish_test

}


proc chng {date desc} {
  puts "<DT><B>$date</B></DT>"
  puts "<DD><P><UL>$desc</UL></P></DD>"
}

chng {2002 Apr 02 (2.4.6)} {
<li>Bug fix: Correctly handle terms in the WHERE clause of a join that
    do not contain a comparison operator.</li>
}

chng {2002 Apr 01 (2.4.5)} {
<li>Bug fix: Correctly handle functions that appear in the WHERE clause
    of a join.</li>
<li>When the PRAGMA vdbe_trace=ON is set, correctly print the P3 operand
    value when it is a pointer to a structure rather than a pointer to
    a string.</li>
<li>When inserting an explicit NULL into an INTEGER PRIMARY KEY, convert
    the NULL value into a unique key automatically.</li>
}