mysqlsqlsubquerysql-deletein-subquery

MySQL DELETE FROM with subquery as condition


I am trying to do a query like this:

DELETE FROM term_hierarchy AS th
WHERE th.parent = 1015 AND th.tid IN (
    SELECT DISTINCT(th1.tid)
    FROM term_hierarchy AS th1
    INNER JOIN term_hierarchy AS th2 ON (th1.tid = th2.tid AND th2.parent != 1015)
    WHERE th1.parent = 1015
);

As you can probably tell, I want to delete the parent relation to 1015 if the same tid has other parents. However, that yields me a syntax error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AS th
WHERE th.parent = 1015 AND th.tid IN (
  SELECT DISTINCT(th1.tid)
  FROM ter' at line 1

I have checked the documentation, and run the subquery by itself, and it all seems to check out. Can anyone figure out what's wrong here?

Update: As answered below, MySQL does not allow the table you're deleting from be used in a subquery for the condition.


Solution

  • You cannot specify target table for delete.

    A workaround

    create table term_hierarchy_backup (tid int(10)); <- check data type
    
    insert into term_hierarchy_backup 
    SELECT DISTINCT(th1.tid)
    FROM term_hierarchy AS th1
    INNER JOIN term_hierarchy AS th2 ON (th1.tid = th2.tid AND th2.parent != 1015)
    WHERE th1.parent = 1015;
    
    DELETE FROM term_hierarchy AS th
    WHERE th.parent = 1015 AND th.tid IN (select tid from term_hierarchy_backup);