While working on a system I'm creating, I attempted to use the following query in my project:
SELECT topics.id, topics.name, topics.post_count, topics.view_count, COUNT( posts.solved_post ) AS solved_post, (SELECT users.username AS posted_by, users.id AS posted_by_id FROM users WHERE users.id = posts.posted_by) FROM topics LEFT OUTER JOIN posts ON posts.topic_id = topics.id WHERE topics.cat_id = :cat GROUP BY topics.id
":cat" is bound by my PHP code as I'm using PDO. 2 is a valid value for ":cat".
That query though gives me an error: "#1241 – Operand should contain 1 column(s)"
What stumps me is that I would think that this query would work no problem. Selecting columns, then selecting two more from another table, and continuing on from there. I just can't figure out what the problem is.
Is there a simple fix to this, or another way to write my query?