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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