MySQL query - getting not inserted ids to insert new row to a table

Question

I have two tables

the first one is process

and the second one is medialist

I want to insert a new row to process but I need a medialist.id which is not inserted by a user before.

select medialist_id from process where user_id=648 -> this returns the inserted rows.

I want those rows excluded from medialist table and get a random medialist id to insert new row to medialist table.

What is the best cost efficient way to do this?

Answer 1

INSERT INTO process (user_id,ads_id,medialist_id,`status`) SELECT 'your_uid','your_ads_id',id,'your_status' FROM medialist WHERE id NOT IN (SELECT medialist_id FROM process) ORDER BY RAND() LIMIT 1