> I'd prefer to omit fields if explicitly assigned to NULL. You can > always use coalesce if you want the string 'NULL'; I agree with > others here that the vast majority of users will want the field > just omitted.
+1
Unfortunately those writing the SQL standard chose to have a single flag (NULL) to indicate either "unknown" or "not applicable". That causes problems where it's not clear which way the value should be interpreted, but in this case it seems pretty clear that someone passing a NULL parameter for hint to a function like this doesn't mean "there is likely to be a valid value for hint, but I don't know what it is" -- they mean there is no available hint, so please don't show one. Any other behavior seems rather silly.
