fetching data from mysql

Question

MySQL

there are 2 tables, I need to select only those rows that are not in the first table when compared with the second, there are developments,

SELECT * FROM `plug_cat_join_item_attr` as zz
RIGHT JOIN `plug_cat_join_cat_item` as xx on xx.`id` = zz.`item`
GROUP BY xx.`id`

but I can't separate them , I need id's in front of NULL

Answer 1

Well, add the condition WHERE zz.`id` IS NULL
Well, the famous link in similar questions:
blog.codinghorror.com/a-visual-explanation-of-sql-joins