Invalid Use of Null ??

[mishbaker]

I have this code in my form to check and see if a DOC# has already been used and return the ITEM# of the item it was assigned to if it has been used. Otherwise it should return a NULL value.

stDOCUsed = DLookup("[Item]", "PartsRequestData", "[DOC] = '" & Me![frmSUBAssignDocs].Form![txt1].Value & "'")

But everytime I run it I get the little box with "Invalid Use of Null" in it.

How is that an invalid use of null??? Is there a valid use??

All lessons learned from the School of Hard Knocks........at least tuition is cheap.

 

[ZmrAbdulla]

stDOCUsed = [b][COLOR=blue]Nz([/color][/b]DLookup("[Item]", "PartsRequestData", "[DOC] = '" & Me![frmSUBAssignDocs].Form![txt1].Value & "'")[b][COLOR=blue], " ")[/color][/b]

________________________________________
Zameer Abdulla
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A child may not be able to lift too much.
But it can certainly hold a marriage together

 

[gwinn7]

You can't assign a NULL to a string variable in VBA.

Gary
gwinn7
A+,N+,L+,I+

 

[TheAceMan1]

ZmrAbdulla . . . . .

I believe its your intent to return an empty string:

 [purple][b]""[/b][/purple]  not [purple][b]" "[/b][/purple]

See Ya! . . . . . .

 

[ZmrAbdulla]

TheAceman1,Yes you are right.
But I have tested it and no error was there.
Thank you for notifying.

________________________________________
Zameer Abdulla
Visit Me
A child may not be able to lift too much.
But it can certainly hold a marriage together

 

[TheAceMan1]

ZmrAbdulla . . . . .

[blue]My point is: Although Access converts spaces only text to a null string when a record is saved, [purple]while the record is dirty, a check for an empty string would fail![/purple][/blue]

See Ya! . . . . . .

 

[ZmrAbdulla]

I normally add Trim() if I need to test null string

________________________________________
Zameer Abdulla
Visit Me
A child may not be able to lift too much.
But it can certainly hold a marriage together