Question

I have this MySQL question. It works fine, but it’s extremly slow. It takes up to 30 seconds to run.

SELECT t.Id, Subject, k.info
FROM tip t
LEFT JOIN comments k ON t.Id = k.Tipid
WHERE event = 1
AND k.Id
IN (
SELECT Max(Id) FROM comments GROUP BY Tipid
)

If I run only the subquery (SELECT Max(Id) FROM comments GROUP BY Tipid) it takes about 0.02 seconds to run.

Something is wrong with the subquery. Do you have any ideas?

Answer 1

you dont need group by if you select max(id) try this

    SELECT t.Id, Subject, k.info
    FROM tip t
    LEFT JOIN comments k ON t.Id = k.Tipid
    WHERE event = 1
    AND k.Id in (select Max(Id) from comments)