This is probably what you are looking for:

SELECT m.subject,m.status,u.user_id
FROM messages m
LEFT JOIN user u ON m.sender_user_id=u.user_id
WHERE u.user_id IS NULL

That will give you all message without a related user.

On Dec 8, 2004, at 6:30 AM, Merlin wrote:

Hi there,

I know this is a question for the mysql mailing list, but maybe one of you guys also could help out with that.

I do have to tables (users, messages). Now there unfortunatelly are some messages where the sender in the user table is missing.

I am trying to find all messages which do not have the belonging user anymore.

So I tried this:
SELECT m.subject, m.status
FROM user u, messages m
WHERE   m.sender_user_id != u.user_id

But this returns far to many rows.

Has anybody an idea how to do that?

Thank you in advance,


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Brent Baisley
Systems Architect
Landover Associates, Inc.
Search & Advisory Services for Advanced Technology Environments
p: 212.759.6400/800.759.0577

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