RE: SQL UPDATE using INNER JOIN?

["DeLong, Eric" <EDeLong@xxxxxxxxxxxxxxx>]

Yes, EXISTS will allow SQL to use an index to determine whether the match is
found, versus compiling a list of all possible matches and looking up your
target row in this list.  

The IN syntax is great for short lists, but as I recall, it forces SQL into
a table scan, where each record must be parsed for eligibility.  

Eric DeLong
Sally Beauty Company
MIS-Project Manager (BSG)
940-297-2863 or ext. 1863



-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of Ron Adams
Sent: Monday, January 16, 2006 4:04 PM
To: Midrange Systems Technical Discussion
Subject: Re: SQL UPDATE using INNER JOIN?


Is there any difference/advantage to using the EXISTS vs the IN clause? This
is the way I'm currently trying to do it. However, The whole reason for
researching the INNER JOIN was due to this taking a really long time to run.
When the IN clause is used it would appear to be re-querying the table for
every record. You can imagine the overhead and time involved if there are
several hundred thousand records.