PHP从MySQL中删除两个表不匹配的行

Question

I have two tables:

tickets
tickets_updates

I think there are a few extra rows in tickets_updates where a record doesn't exist in the tickets table

What is the best way to run SQL Code to say:

Delete all from tickets_updates where ticket_seq is not in tickets (sequence)

sequence in the tickets table matches ticket_seq in the tickets_updates table

Answer 1

DELETE FROM tickets_updates
WHERE  ticket_seq NOT IN (SELECT sequence
                           FROM   tickets)  

Answer 2

DELETE FROM tickets_updates tu
LEFT JOIN tickets t ON tu.ticket_seq = t.sequence
WHERE t.sequence IS NULL

Answer 3

Try this:

DELETE FROM ticket_updates
WHERE NOT EXISTS
    (SELECT 'x' from tickets
    WHERE tickets.sequence = ticket_updates.ticket_seq)