as far as I know, it's not possible to check specifically for NULL value in workflow, resp. NULL and empty value are considered to be same.

CAML has IsNull/IsNotNull check but for it NULL and empty value are the same as well.

what's the source of your variable value? does it differentiate NULL and empty value at all?

Hi Marian,

Thanks for replying so quickly.  Long story short the variable value is populated as the result of a query to a database.  I am hearing from the developer of the querry that one of the possible results is a null value.  That being the case I am trying to figure out a way to determine if the variable contains a null so that I can error handle it.  I am surprised that is empty would also check for isnull as I would suspect those to be two different conditions.  Have you been able to validate that or are you aware of any documentation that shows that?  It would be great if that were true as that would essentially solve my problem.

Note: Ideally it would be great if I could have the query remove a null result but in this case it actually identifies an issue that needs to be resolved.

Thanks again for your response.

then I would definitely dealt with that on database level.

why database accepts NULLs, if it is "error case"?

I understand you may not have influence on database design.

but does it make difference in your workflow processing if you get NULL or empty value? if you eg. process some end user inputs you anyway can not distinct it. users (usually) have no clue what's the difference between the two and have no ways to input one the other.

however, if you really need to distinguish NULL and empty values in workflow then I'd suggest you ask your database developer to provide you with sufficient information. eg. to publish two queries, one with 'is not null' and second with 'is null' condition, or some extra flag that will tell you whether a column with no value is just empty or NULL.