Thanks.

I went down this same road about 8 weeks ago - trying to create a check constraint using a UDF, finding it works for inserts but not updates, then finding that SQL 08 allows for filtered indexes and using that instead. Somehow, I forgot all about that when the same situation arose again.

I'll keep in mind your advise regarding avoidance of UDFs for constraints.

One more thing - do you know if MySQL allows for filtered indexes? I don't think it does based on my searching.

Thanks again.