At 03:43 PM 10/6/05, Hector Rosas wrote:
Hello, I'm trying to select records in a table not present in a related
table, in example, I've a table with message information (subject,
message, date, etc) and another (usermessages) with where user(s) has that
message, its state, etc. Records in this table will be deleted in a
certain time (just some extra info).
I want to select messages records that aren't present in the other table
(usermessages), I got the next two queries, maybe someone can suggest a
better one.
SELECT <http://m.id>m.id FROM messages AS m
WHERE (SELECT count(um.*) FROM usermessages AS um WHERE um.idmessage=m.id )=0;
SELECT <http://m.id>m.id FROM messages AS m where id NOT IN (select
um.idmessage FROM usermessages um);
select m.id from messages as m left join usermessages as um on
m.id=um.idmessage where um.idmessage is null;
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