Question

I am trying to fire below query…

Is there any problem in it?

delete from user_role 
WHERE user_id in (
    select u.user_id from user u, user_role ur 
    where u.USER_ID=ur.USER_ID and ur.ROLE_ID=4 and u.USER_ID not in (
        select user_id from referrers));

Answer 1

As stated in the manual section on DELETE Syntax:

Currently, you cannot delete from a table and select from the same table in a subquery.

You can instead use the multiple-table form of DELETE and join together your tables:

DELETE user_role
FROM   user_role
  INNER JOIN user_id   USING (USER_ID)
  LEFT  JOIN referrers USING (USER_ID)
WHERE user_role.ROLE_ID = 4 AND referrers.USER_ID IS NULL