delete where not in another table - Mailing list pgsql-sql

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 T2.user_id=T1.user_id);

I was thinking there should be a way to write this with a join.

Thanks,

Lance Campbell

Software Architect

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