I think the OUTER JOIN version is probably more efficient, but EXPLAIN
would tell you.
-tfo
On Oct 8, 2004, at 8:02 AM, CHRIS HOOVER wrote:
Just curious, what is wrong with the first way of coding the solution?
------------------( Forwarded letter 1 follows )---------------------
Date: Fri, 8 Oct 2004 08:44:23 +0400
To: Thomas.F.O'[EMAIL PROTECTED], [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
From: [EMAIL PROTECTED]
Sender: [EMAIL PROTECTED]
Subject: Re: [SQL] help on a query
On Friday 08 October 2004 07:10, Thomas F.O'Connell wrote:
A query that should get the job done is:
SELECT registration_id
FROM registrations r
WHERE NOT EXISTS (
SELECT 1
FROM receipts
WHERE registration_id = r.registration_id
);
Don't, PLEASE, don't !!!
drive this way :
SELECT r.registration_id
FROM registrations AS r
LEFT OUTER JOIN receipts AS rec
ON rec.registration_id = r.registration_id
WHERE rec.registration_id IS NULL;
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