I have two SQL tables "user" and "entries".
I want to check with only one query if the user exists in first Table "user" or not and if the user has maked an entry in table "Entries" or not.
I want to make something like rating system. Where user should exist in table "user" and has no Entries in Table "entries". Because every user can make only one entry.
Is it possible to do it with only one query, how can i do it?
I know only how can i do it with two queries
SELECT COUNT(*) amount FROM user
SELECT COUNT(*) quantity FROM entries WHERE user_id = $userID
You should use the "NOT EXISTS" operator:
SELECT id FROM user WHERE id = $userID AND NOT EXISTS (SELECT * FROM entries where user_id = $userID);
It will return a row only if the user exists in the table "user" and has no entries in the table "entries".