SQL DELETE with JOIN another table for WHERE condition

Question

I have to delete rows from guide_category that have no relation with guide table (dead relations).

Here is what I want to do, but it of cou

Answer 1

I think, from your description, the following would suffice:

DELETE FROM guide_category 
WHERE id_guide NOT IN (SELECT id_guide FROM guide)

I assume, that there are no referential integrity constraints on the tables involved, are there?