database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-07 02:42:48 +03:00
Code Activity

Refinements to NULL processing: NULLs are indistinct for DISTINCT and UNION.

Browse Source 
Multiplying a NULL by zero yields zero. In a CASE expression, a NULL comparison
is considered false, not NULL.  With these changes, NULLs in SQLite now work
the same as in PostgreSQL and in Oracle. (CVS 600)

FossilOrigin-Name: da61aa1d238539dff9c43fd9f464d311e28d669f
This commit is contained in:
drh
2002-05-31 15:51:25 +00:00
parent 0f89253e21
commit f570f011eb
11 changed files with 279 additions and 59 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
src/vdbe.c
View File

@@ -30,7 +30,7 @@
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.150 2002/05/27 01:04:51 drh Exp $
** $Id: vdbe.c,v 1.151 2002/05/31 15:51:26 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1769,9 +1769,28 @@ case OP_Remainder: {
int nos = tos - 1;
VERIFY( if( nos<0 ) goto not_enough_stack; )
if( ((aStack[tos].flags | aStack[nos].flags) & STK_Null)!=0 ){
int resultType = STK_Null;
if( pOp->opcode==OP_Multiply ){
/* Special case: multiplying NULL by zero gives a zero result, not a
** NULL result as it would normally. */
if( (aStack[tos].flags & (STK_Int|STK_Real))!=0
|| ((aStack[tos].flags & STK_Str)!=0 && isNumber(zStack[tos])) ){
Integerify(p,tos);
if( aStack[tos].i==0 ){
resultType = STK_Int;
aStack[nos].i = 0;
}
}else if( (aStack[nos].flags & (STK_Int|STK_Real))!=0
|| ((aStack[nos].flags & STK_Str)!=0 && isNumber(zStack[nos])) ){
Integerify(p,nos);
if( aStack[nos].i==0 ){
resultType = STK_Int;
}
}
}
POPSTACK;
Release(p, nos);
aStack[nos].flags = STK_Null;
aStack[nos].flags = resultType;
}else if( (aStack[tos].flags & aStack[nos].flags & STK_Int)==STK_Int ){
int a, b;
a = aStack[tos].i;
@@ -2346,6 +2365,10 @@ case OP_NotNull: {
** created this way will not necessarily be distinct across runs.
** But they should be distinct for transient tables (created using
** OP_OpenTemp) which is what they are intended for.
**
** (Later:) The P2==1 option was intended to make NULLs distinct
** for the UNION operator. But I have since discovered that NULLs
** are indistinct for UNION. So this option is never used.
*/
case OP_MakeRecord: {
char *zNewRecord;