SQLite

2.5.1

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.38 2002/06/19 14:27:05 drh Exp $
*/
#include "sqliteInt.h"


/*
** Given a table name, find the corresponding table and make sure the
** table is writeable.  Generate an error and return NULL if not.  If

  /* The usual case: There is a WHERE clause so we have to scan through
  ** the table an pick which records to delete.
  */
  else{
    /* Begin the database scan
    */
    pWInfo = sqliteWhereBegin(pParse, base, pTabList, pWhere, 1, 0);
    if( pWInfo==0 ) goto delete_from_cleanup;

    /* Remember the key of every item to be deleted.
    */
    sqliteVdbeAddOp(v, OP_ListWrite, 0, 0);
    if( db->flags & SQLITE_CountRows ){
      sqliteVdbeAddOp(v, OP_AddImm, 1, 0);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.94 2002/06/19 14:27:05 drh Exp $
*/
#include "sqliteInt.h"

/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/

    sqliteVdbeAddOp(v, OP_OpenTemp, distinct, 1);
  }else{
    distinct = -1;
  }

  /* Begin the database scan
  */
  pWInfo = sqliteWhereBegin(pParse, p->base, pTabList, pWhere, 0, &pOrderBy);
  if( pWInfo==0 ) goto select_end;

  /* Use the standard inner loop if we are not dealing with
  ** aggregates
  */
  if( !isAgg ){
    if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
                    iParm, pWInfo->iContinue, pWInfo->iBreak) ){
       goto select_end;
    }
  }

  /* If we are dealing with aggregates, then do the special aggregate
  ** processing.  
  */
  else{
    if( pGroupBy ){
      int lbl1;
      for(i=0; i<pGroupBy->nExpr; i++){
        sqliteExprCode(pParse, pGroupBy->a[i].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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.126 2002/06/19 14:27:05 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>

                        int,int,int);
void sqliteSelectDelete(Select*);
void sqliteSelectUnbind(Select*);
Table *sqliteTableNameToTable(Parse*, const char*);
SrcList *sqliteTableTokenToSrcList(Parse*, Token*);
void sqliteDeleteFrom(Parse*, Token*, Expr*);
void sqliteUpdate(Parse*, Token*, ExprList*, Expr*, int);
WhereInfo *sqliteWhereBegin(Parse*, int, SrcList*, Expr*, int, ExprList**);
void sqliteWhereEnd(WhereInfo*);
void sqliteExprCode(Parse*, Expr*);
void sqliteExprIfTrue(Parse*, Expr*, int, int);
void sqliteExprIfFalse(Parse*, Expr*, int, int);
Table *sqliteFindTable(sqlite*,const char*);
Index *sqliteFindIndex(sqlite*,const char*);
void sqliteUnlinkAndDeleteIndex(sqlite*,Index*);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.45 2002/06/19 14:27:06 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(

  */
  v = sqliteGetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  sqliteBeginWriteOperation(pParse, 1);

  /* Begin the database scan
  */
  pWInfo = sqliteWhereBegin(pParse, base, pTabList, pWhere, 1, 0);
  if( pWInfo==0 ) goto update_cleanup;

  /* Remember the index of every item to be updated.
  */
  sqliteVdbeAddOp(v, OP_ListWrite, 0, 0);

  /* End the database scan loop.

**    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 1.53 2002/06/19 14:27:06 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 */
  u8 indexable;           /* True if this subexprssion is usable by an index */
  short int idxLeft;      /* p->pLeft is a column in this table number. -1 if
                          ** p->pLeft is not the column of any table */
  short int idxRight;     /* p->pRight is a column in this table number. -1 if
                          ** p->pRight is not the column of any table */
  unsigned prereqLeft;    /* Bitmask of tables referenced by p->pLeft */
  unsigned prereqRight;   /* Bitmask of tables referenced by p->pRight */
  unsigned prereqAll;     /* Bitmask of tables referenced by p */
};

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

  }
  return cnt;
}

/*
** This routine walks (recursively) an expression tree and generates
** a bitmask indicating which tables are used in that expression
** tree.  Bit 0 of the mask is set if table base+0 is used.  Bit 1
** is set if table base+1 is used.  And so forth.
**
** In order for this routine to work, the calling function must have
** previously invoked sqliteExprResolveIds() on the expression.  See
** the header comment on that routine for additional information.
**
** "base" is the cursor number (the value of the iTable field) that
** corresponds to the first entry in the list of tables that appear
** in the FROM clause of a SELECT.  For UPDATE and DELETE statements
** there is just a single table with "base" as the cursor number.
*/
static int exprTableUsage(int base, Expr *p){
  unsigned int mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    return 1<< (p->iTable - base);
  }

      pInfo->idxLeft = pExpr->pLeft->iTable - base;
      pInfo->indexable = 1;
    }
  }
}

/*
** pOrderBy is an ORDER BY clause from a SELECT statement.  pTab is the
** left-most table in the FROM clause of that same SELECT statement and
** the table has a cursor number of "base".
**
** This routine attempts to find an index for pTab that generates the
** correct record sequence for the given ORDER BY clause.  The return value
** is a pointer to an index that does the job.  NULL is returned if the
** table has no index that will generate the correct sort order.
**
** If there are two or more indices that generate the correct sort order
** and pPreferredIdx is one of those indices, then return pPreferredIdx.
*/
static Index *findSortingIndex(
  Table *pTab,            /* The table to be sorted */
  int base,               /* Cursor number for pTab */
  ExprList *pOrderBy,     /* The ORDER BY clause */
  Index *pPreferredIdx    /* Use this index, if possible and not NULL */
){
  int i;
  Index *pMatch;
  Index *pIdx;

  assert( pOrderBy!=0 );
  assert( pOrderBy->nExpr>0 );
  for(i=0; i<pOrderBy->nExpr; i++){
    Expr *p;
    if( (pOrderBy->a[i].sortOrder & SQLITE_SO_DIRMASK)!=SQLITE_SO_ASC ){
      /* Indices can only be used for ascending sort order */
      return 0;
    }
    p = pOrderBy->a[i].pExpr;
    if( p->op!=TK_COLUMN || p->iTable!=base ){
      /* Can not use an index sort on anything that is not a column in the
      ** left-most table of the FROM clause */
      return 0;
    }
  }

  /* If we get this far, it means the ORDER BY clause consists only of
  ** ascending columns in the left-most table of the FROM clause.  Now
  ** check for a matching index.
  */
  pMatch = 0;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    if( pIdx->nColumn<pOrderBy->nExpr ) continue;
    for(i=0; i<pOrderBy->nExpr; i++){
      if( pOrderBy->a[i].pExpr->iColumn!=pIdx->aiColumn[i] ) break;
    }
    if( i>=pOrderBy->nExpr ){
      pMatch = pIdx;
      if( pIdx==pPreferredIdx ) break;
    }
  }
  return pMatch;
}

/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an (opaque) structure that contains
** information needed to terminate the loop.  Later, the calling routine
** should invoke sqliteWhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.
**
** If an error occurs, this routine returns NULL.
**

**    foreach row1 in t1 do
**      flag = 0
**      foreach row2 in t2 do
**        start:
**          ...
**          flag = 1
**      end
**      if flag==0 then
**        move the row2 cursor to a null row
**        goto start
**      fi
**    end
**
** ORDER BY CLAUSE PROCESSING
**
** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
** if there is one.  If there is no ORDER BY clause or if this routine
** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL.
**
** If an index can be used so that the natural output order of the table
** scan is correct for the ORDER BY clause, then that index is used and
** *ppOrderBy is set to NULL.  This is an optimization that prevents an
** unnecessary sort of the result set if an index appropriate for the
** ORDER BY clause already exists.
**
** If the where clause loops cannot be arranged to provide the correct
** output order, then the *ppOrderBy is unchanged.
*/
WhereInfo *sqliteWhereBegin(
  Parse *pParse,       /* The parser context */
  int base,            /* VDBE cursor index for left-most table in pTabList */
  SrcList *pTabList,   /* A list of all tables to be scanned */
  Expr *pWhere,        /* The WHERE clause */
  int pushKey,         /* If TRUE, leave the table key on the stack */
  ExprList **ppOrderBy /* An ORDER BY clause, or NULL */
){
  int i;                     /* Loop counter */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
  int brk, cont;             /* Addresses used during code generation */
  int *aOrder;         /* Order in which pTabList entries are searched */
  int nExpr;           /* Number of subexpressions in the WHERE clause */
  int loopMask;        /* One bit set for each outer loop */
  int haveKey;         /* True if KEY is on the stack */
  int aDirect[32];     /* If TRUE, then index this table using ROWID */
  int iDirectEq[32];   /* Term of the form ROWID==X for the N-th table */
  int iDirectLt[32];   /* Term of the form ROWID<X or ROWID<=X */
  int iDirectGt[32];   /* Term of the form ROWID>X or ROWID>=X */
  ExprInfo aExpr[50];  /* The WHERE clause is divided into these expressions */

  /* pushKey is only allowed if there is a single table (as in an INSERT or
  ** UPDATE statement)
  */
  assert( pushKey==0 || pTabList->nSrc==1 );
  
  /* Allocate space for aOrder[] */
  aOrder = sqliteMalloc( sizeof(int) * pTabList->nSrc );

  /* Allocate and initialize the WhereInfo structure that will become the
  ** return value.
  */
  pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
  if( sqlite_malloc_failed ){

    pWInfo->a[i].score = bestScore;
    loopMask |= 1<<idx;
    if( pBestIdx ){
      pWInfo->a[i].iCur = pParse->nTab++;
      pWInfo->peakNTab = pParse->nTab;
    }
  }

  /* Check to see if the ORDER BY clause is or can be satisfied by the
  ** use of an index on the first table.
  */
  if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){
     Index *pSortIdx;
     Index *pIdx;
     Table *pTab;

     pTab = pTabList->a[0].pTab;
     pIdx = pWInfo->a[0].pIdx;
     if( pIdx && pWInfo->a[0].score==4 ){
       /* If there is already an index on the left-most column and it is
       ** an equality index, then either sorting is not helpful, or the
       ** index is an IN operator, in which case the index does not give
       ** the correct sort order.  Either way, pretend that no suitable
       ** index is found.
       */
       pSortIdx = 0;
     }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
       /* If the left-most column is accessed using its ROWID, then do
       ** not try to sort by index.
       */
       pSortIdx = 0;
     }else{
       pSortIdx = findSortingIndex(pTab, base, *ppOrderBy, pIdx);
     }
     if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
       if( pIdx==0 ){
         pWInfo->a[0].pIdx = pSortIdx;
         pWInfo->a[0].iCur = pParse->nTab++;
         pWInfo->peakNTab = pParse->nTab;
       }
       *ppOrderBy = 0;
     }
  }

  /* Open all tables in the pTabList and all indices used by those tables.
  */
  for(i=0; i<pTabList->nSrc; i++){
    int openOp;
    Table *pTab;

      }
      aExpr[k].p = 0;
      cont = pLevel->cont = sqliteVdbeMakeLabel(v);
      sqliteVdbeAddOp(v, OP_MustBeInt, 0, brk);
      haveKey = 0;
      sqliteVdbeAddOp(v, OP_NotExists, base+idx, brk);
      pLevel->op = OP_Noop;
    }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){
      /* Case 2:  There is an index and all terms of the WHERE clause that
      **          refer to the index use the "==" or "IN" operators.
      */
      int start;
      int testOp;
      int nColumn = pLevel->score/4;
      brk = pLevel->brk = sqliteVdbeMakeLabel(v);

    }else{
      /* Case 5: The WHERE clause term that refers to the right-most
      **         column of the index is an inequality.  For example, if
      **         the index is on (x,y,z) and the WHERE clause is of the
      **         form "x=5 AND y<10" then this case is used.  Only the
      **         right-most column can be an inequality - the rest must
      **         use the "==" operator.
      **
      **         This case is also used when there are no WHERE clause
      **         constraints but an index is selected anyway, in order
      **         to force the output order to conform to an ORDER BY.
      */
      int score = pLevel->score;
      int nEqColumn = score/4;
      int start;
      int leFlag, geFlag;
      int testOp;

# 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 1.9 2002/06/19 14:27:06 drh Exp $

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

# Build some test data
#
do_test where-1.0 {

  count {SELECT w FROM t1 WHERE w<3}
} {1 2 4}
do_test where-1.36 {
  count {SELECT w FROM t1 WHERE w<=3}
} {1 2 3 6}
do_test where-1.37 {
  count {SELECT w FROM t1 WHERE w+1<=4 ORDER BY w}
} {1 2 3 199}


# Do the same kind of thing except use a join as the data source.
#
do_test where-2.1 {
  count {
    SELECT w, p FROM t2, t1

    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 16 199}
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 16 199}
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 25 199}
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 25 199}
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 16 199}
do_test where-5.11 {
  count {
    SELECT * FROM t1 WHERE y IN (6400,8100) ORDER BY 1;
  }
} {79 6 6400 89 6 8100 199}
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}

# This procedure executes the SQL.  Then it checks the generated program
# for the SQL and appends a "nosort" to the result if the program contains the
# SortCallback opcode.  If the program does not contain the SortCallback
# opcode it appends "sort"
#
proc cksort {sql} {
  set data [execsql $sql]
  set prog [execsql "EXPLAIN $sql"]
  if {[regexp SortCallback $prog]} {set x sort} {set x nosort}
  lappend data $x
  return $data
}
# Check out the logic that attempts to implement the ORDER BY clause
# using an index rather than by sorting.
#
do_test where-6.1 {
  execsql {
    CREATE TABLE t3(a,b,c);
    CREATE INDEX t3a ON t3(a);
    CREATE INDEX t3bc ON t3(b,c);
    CREATE INDEX t3acb ON t3(a,c,b);
    INSERT INTO t3 SELECT w, 101-w, y FROM t1;
    SELECT count(*), sum(a), sum(b), sum(c) FROM t3;
  }
} {100 5050 5050 348550}
do_test where-6.2 {
  cksort {
    SELECT * FROM t3 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 nosort}
do_test where-6.3 {
  cksort {
    SELECT * FROM t3 ORDER BY a+1 LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 sort}
do_test where-6.4 {
  cksort {
    SELECT * FROM t3 WHERE a<10 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 nosort}
do_test where-6.5 {
  cksort {
    SELECT * FROM t3 WHERE a>0 AND a<10 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 nosort}
do_test where-6.6 {
  cksort {
    SELECT * FROM t3 WHERE a>0 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 nosort}
do_test where-6.7 {
  cksort {
    SELECT * FROM t3 WHERE b>0 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 sort}
do_test where-6.8 {
  cksort {
    SELECT * FROM t3 WHERE a IN (3,5,7,1,9,4,2) ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 sort}
do_test where-6.9 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.10 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.11 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a,c LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.12 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a,c,b LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.13 {
  cksort {
    SELECT * FROM t3 WHERE a>0 ORDER BY a DESC LIMIT 3
  }
} {100 1 10201 99 2 10000 98 3 9801 sort}
do_test where-6.14 {
  cksort {
    SELECT * FROM t3 ORDER BY b LIMIT 3
  }
} {100 1 10201 99 2 10000 98 3 9801 nosort}
do_test where-6.15 {
  cksort {
    SELECT t3.a, t1.x FROM t3, t1 WHERE t3.a=t1.w ORDER BY t3.a LIMIT 3
  }
} {1 0 2 1 3 1 nosort}
do_test where-6.16 {
  cksort {
    SELECT t3.a, t1.x FROM t3, t1 WHERE t3.a=t1.w ORDER BY t1.x, t3.a LIMIT 3
  }
} {1 0 2 1 3 1 sort}


finish_test

}


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

chng {2002 Jun 19 (2.5.1)} {
<li>The query optimizer now attempts to implement the ORDER BY clause
    using an index.  Sorting is still used if not suitable index is
    available.</li>
}

chng {2002 Jun 17 (2.5.0)} {
<li>Added support for row triggers.</li>
<li>Added SQL-92 compliant handling of NULLs.</li>
<li>Add support for the full SQL-92 join syntax and LEFT OUTER JOINs.</li>
<li>Double-quoted strings interpreted as column names not text literals.</li>
<li>Parse (but do not implement) foreign keys.</li>