Question

I got the IDs(the rows to be updated) in this query from post table, with those IDs as rows in grade table, I want to set one var to 1, and others in this array to 0, and keep the rest rows in the grade table unchanged:

SELECT ID FROM posts
WHERE post_parent = ''
AND post_status IN ( '')
AND post_type = ''

I’d like to learn how to update the grade table as described above. Thanks!

Answer 1

You can use this solution:

UPDATE grade g
JOIN   post p ON g.id          = p.id
             AND p.post_parent = $parent_id
             AND p.post_status = $post_status
             AND p.post_type   = $post_type
SET    g.grade = CASE WHEN g.id = $id THEN 1 ELSE 0 END