Question

I’m trying to change the following query into one that deletes the returned rows.

SELECT bad_rows.*
FROM votes as bad_rows
INNER JOIN(
    SELECT  MIN(id) as min_id, votes.object_id, votes.user_id 
FROM votes WHERE is_archived=FALSE AND 
     votes.direction < 20 
GROUP BY votes.object_id, votes.user_id, votes.content_type_id
having COUNT(votes.object_id) > 1
) AS double_rows ON 
    double_rows.object_id = bad_rows.object_id 
    AND double_rows.user_id=bad_rows.user_id 
    AND bad_rows.is_archived=False
    AND double_rows.min_id <> bad_rows.id

this select works and gives me the rows I want to delete. Now if i change the select into a delete my query does not work.

DELETE bad_rows.*
FROM votes as bad_rows
INNER JOIN(
    SELECT  MIN(id) as min_id, votes.object_id, votes.user_id 
FROM votes WHERE is_archived=FALSE AND 
     votes.direction < 20 
GROUP BY votes.object_id, votes.user_id, votes.content_type_id
having COUNT(votes.object_id) > 1
) AS double_rows ON 
    double_rows.object_id = bad_rows.object_id 
    AND double_rows.user_id=bad_rows.user_id 
    AND bad_rows.is_archived=False
    AND double_rows.min_id <> bad_rows.id

ERROR: syntax error at or near “bad_rows”
LINE 1: DELETE bad_rows.*

Answer 1

You can’t specify columns to delete (the * in bad_rows.*.)

Also, most databases do not allow you to specify an alias for deleting. So the usual approach to deleting is something like:

DELETE  VOTES
WHERE   ID IN
        (
        <subquery selecting the ID's of the rows you want to delete>
        )