If you only want to update values in table A when there are matching records in table B, then an inner join is the way to go. If you have calculations that need to vary based on optional data, the ...

You would use Is Null and Is Not Null in query expressions and SQL WHERE clauses. IsNull(), on the other hand, is a Visual Basic for Applications (VBA) function and would be used only in VBA modules.

So in this instance there is data to CRD1.StreetNo, so only card code, street, and block display data, bit city, state, or zip. If I comment out StreetNo, my city, state, and zip appear.