如何在另一张桌子上不存在

Question

How to not exist on another table on this two table?

Users table

User_relationships table

and this is my current query

"SELECT * FROM `users` 
WHERE CONCAT(first_name, " ", last_name) LIKE '%' . $name . '%' 
    AND (`role_id` = 6 OR `role_id` = 4)
ORDER BY `first_name` asc limit 15"

and I want to add on query where guardian_id(user_id) not exist on the user_relationships table

UPDATE 1

select * from `users` 
    where not exists 
            (select 1 from `user_relationships` 
             inner join `users` on `user_relationships`.`guardian_id` = `users`.`id` 
             where `user_relationships`.`student_id` = 422) 

I tried this and still returns me zero result.

I only have var name = ? and student_id = ?

Answer 1

try to use "NOT IN" query function with 'DISTINCT'.

following may help you.

select * from users where CONCAT(first_name, " ", last_name) LIKE '%' . $name . '%' and (role_id= 6 or role_id= 4) and (id NOT IN (select DISTINCT guardian_id from User_relationships where student_id = $student_id)) order by first_name ASC limit 15

Let me know if you still need some changes.