This sounds like a perfect candidate for a LEFT OUTER JOIN. See:
http://www.postgresql.org/docs/7.4/static/queries-table- expressions.html#QUERIES-FROM
Yours would looks something like:
SELECT * FROM ... LEFT JOIN candidate AS c ON <...>.omcr_id = c.omcr_id AND ...
-tfo
-- Thomas F. O'Connell Co-Founder, Information Architect Sitening, LLC http://www.sitening.com/ 110 30th Avenue North, Suite 6 Nashville, TN 37203-6320 615-260-0005
On Jan 30, 2005, at 1:41 PM, Don Drake wrote:
OK, I have a function that finds records that changed in a set of tables and attempts to insert them into a data warehouse.
There's a large outer loop of candidate rows and I inspect them to see if the values really changed before inserting.
My problem is that when I look to see if the row exists in the warehouse already, based on some IDs, it fails when an ID is NULL. The ID is nullable, so that's not a problem.
But I'm forced to write an IF statement looking for the potential NULL and write 2 queries:
IF omcr_id is null select * from .... WHERE omcr_id is NULL AND ... ELSE select * from .... WHERE omcr_id=candidate.omcr_id AND .... END IF;
IF FOUND ...
Is there a way to do the lookup in one statement?? This could get ugly quick. I'm using v7.4.
Thanks.
-Don
-- Donald Drake President Drake Consulting http://www.drakeconsult.com/ 312-560-1574
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