Question

I get an error (1064) when attempting to run the following… (MySql 5.5.9)

query:

CREATE TRIGGER clearChat AFTER INSERT ON chat
FOR EACH ROW
BEGIN
DELETE p.* FROM chat p LEFT JOIN (SELECT t.id FROM chat t ORDER BY t.id DESC LIMIT 50) x ON x.id = p.id WHERE x.id IS NULL
END;

the error is:

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 'END' at line 5

Any assistance would be great.

Last Edit: Updated to show the ‘FOR EACH ROW’ and ‘BEGIN’

Answer 1

You’re missing FOR EACH ROW before DELETE: http://dev.mysql.com/doc/refman/5.1/en/create-trigger.html

Edit: There are more issues. The correct syntax is below:

delimiter |

    CREATE TRIGGER clearChat AFTER INSERT ON chat
      FOR EACH ROW BEGIN
        DELETE p.* FROM chat p LEFT JOIN (SELECT t.id FROM chat t ORDER BY t.id DESC LIMIT 50) x ON x.id = p.id WHERE x.id IS NULL;
      END;
|

delimiter ;

Edit 2:

I don’t think that query is allowed to be in a trigger at all based on this http://dev.mysql.com/doc/refman/5.1/en/faqs-triggers.html#qandaitem-B-5-1-9:

A trigger can access both old and new
data in its own table. A trigger can
also affect other tables, but it is
not permitted to modify a table that
is already being used (for reading or
writing) by the statement that invoked
the function or trigger.

Since you aren’t using OLD or NEW, I don’t think you can modify chat since the trigger is triggered on inserts to chat.