Here is the MySQL query I am using:
SELECT * FROM wc_poems p, wc_poem_cat_link l WHERE p.id=l.poem_id AND (l.cat_id IN (3) OR p.all_cats=1) ORDER BY p.list_order ASC
The query should return a column if all_cats is set to 1, no matter whether the other conditions are met or not. But it only returns if cat_id matches the condition (i.e. it is 3).
Using EXPLAIN I get the message "Impossible WHERE noticed after reading const table..." I though I had some idea of what that meant, but can't put my finger on it.
If somebody could help I would appreciate it. If there is some more information I need to post please let me know.