Re: join query question

From: Brian Tkatch <SPAMBLOCK.Maxwell_Smart_at_ThePentagon.com.SPAMBLOCK>
Date: Fri, 22 Jun 2001 13:40:44 GMT
Message-ID: <3b334a4f.334730546@news.alt.net>

>The 'where not exists ' statement earlier can have detrimental connotations. Try to
>avoid negation and base the seed on what is hopefully an indexed column ( empnum)
>in both source tables.

Why avoid negation? The original request was for everything in A after negating (from a) everything that is in B.

Assuming empnum is indexed on an incrementing id, not exists should be able to traverse the index immediately to find where the id should be and know if it is or is not there. Am I missing some thing about hte was EXISTS works?

Brian Received on Fri Jun 22 2001 - 08:40:44 CDT