> Subject: [SQL] delete where not in another table
> DELETE FROM T1 WHERE T1.user_id NOT IN (SELECT user_id FROM T2 WHERE
> T2.user_id=T1.user_id);
Following query use an anti join and is much faster:
delete from t1 where not exists (select user_id from t2 where t2.user_id
=t
From: pgsql-sql-ow...@postgresql.org [mailto:pgsql-sql-ow...@postgresql.org] On
Behalf Of Campbell, Lance
Sent: Tuesday, July 09, 2013 3:25 PM
To: pgsql-sql@postgresql.org
Subject: [SQL] delete where not in another table
DELETE FROM T1 WHERE T1.user_id NOT IN (SELECT user_id FROM T2 WHERE
T2
If I have two tables, T1 and T2, such that both have the same primary key of
"user_id".
What is the SQL I would use to delete all rows from T1 that are not in T2?
This is one way to write the SQL but it is really inefficient:
DELETE FROM T1 WHERE T1.user_id NOT IN (SELECT user_id FROM T2 WHERE
