Thx. But is it in one of the SQL standards definitions as well ? I am pretty certain Exists was in SQL99, probably already in SQL92.
If Except generates faster execution plans AND is in one of the standards, I'd use it even if not all others support it (yet), as it is expressive.
If it is not standard, my rule of thumb would point to !null, if the speed of not in () or not exists create a problem.


>It is in SQL Server starting from 2005 and up. I am not sure about other vendors such as Oracle or MySQL, someone who uses them may tell.
>
>>Do you happen to know in which SQL (as in 92,99,2003) this is defined and which vendors support it ?
>>