Question

I have a table with several hundred rows. I want to take the top 20 based on the value of column num and replace num with a number.

What I tried to do (which didn’t work) was:

UPDATE table
SET num = 95
WHERE id IN (SELECT id FROM table ORDER BY id DESC LIMIT 20)

Any suggestions?

Answer 1

There’s no need for the subquery – you can use LIMIT in an UPDATE statement on MySQL:

  UPDATE table
     SET num = 95
ORDER BY id DESC
   LIMIT 20

It’s unclear what you want to order by – I used id based on your subquery, but in case it needs to be by the num value:

  UPDATE table
     SET num = 95
ORDER BY num DESC
   LIMIT 20