Hi Sergey,

>I think that it's a bug but to demonstrate that you've to make sure that variablr 'x' has proper type because in you code its type is 'L'.

I was sure of this note, try with:

...
x=VAL(NULL)
...

> Anyway, it doesn't make much sense to search on Null because you know that you wouldn't find anything.

1. If i write generic search class i need to cut the search for any null values:

IF ISNULL(m.searchValue)
  GO BOTTOM
  SKIP
ELSE
  SEEK m.searchValue
ENDIF
IF FOUND()
ENDIF
* this for KEYMATCH,SEEK,INDEXSEEK,.... and for RUSHMORE optimization ?

2. If this is true, why SQL Server support this ?

3. In fact VFP search NULL on index not nullable.

SET NULL ON

CREATE CURSOR MasterTable ( rid I AUTOINCR UNIQUE,Texto C(50) NOT NULL)
INSERT INTO MasterTable (Texto) VALUES ('testo 1')
INSERT INTO MasterTable (Texto) VALUES ('testo 2')

CREATE CURSOR ChilrdTable ( rid I AUTOINCR UNIQUE,linkValue I)
INSERT INTO ChilrdTable (linkValue) VALUES (1)
INSERT INTO ChilrdTable (linkValue) VALUES (NULL)

* SELECT search NULL on index not nullable !!!!
cRush=''
SYS(3054,11,'cRush')
SELECT CH.rid,CH.linkValue,MT.Texto FROM ChilrdTable CH LEFT JOIN MasterTable MT ON MT.rid=CH.linkValue INTO CURSOR r1
? cRush
MESSAGEBOX('SELECT search NULL on index, and return NULL record')

ON ERROR MESSAGEBOX(MESSAGE()+CHR(13)+'LOOKUP not support NULL, ignore error and continue')
SELECT CH.rid,CH.linkValue,LOOKUP(MasterTable.Texto,CH.linkValue,MasterTable.rid) Texto FROM ChilrdTable CH INTO CURSOR r2
ON ERROR

SET ORDER TO 1 IN MasterTable
SELECT ChilrdTable
SET RELATION TO linkValue INTO MasterTable
SCAN
 ? linkValue,MasterTable.Texto,EOF('MasterTable')
ENDSCAN
MESSAGEBOX('RELATION search NULL on index, and go EOF() for NULL')

VFP need a complete, coherent, support for NULL.

Fabio