Subject Re: [firebird-support] Left Join vs Not Exists
Author Ann W. Harrison
Rick Debay wrote:
> I know of two ways to get records from set A that don't exist in set B.

I'd use not exists - the performance will be better, but more important,
the next person who looks at the code will have some prayer of figuring
out what you're trying to do.



Performance will be better if you have multiple B's for some A. The
first B will eliminate the A with a "NOT EXISTS". The outer join has to
check each B it matches to see if the fields are null.