使用phpmyadmin mysql触发语法错误

I need the right syntax for MySQL trigger:

CREATE TRIGGER `parent_comm`    
  BEFORE UPDATE ON `employee` FOR EACH ROW
      BEGIN
       SET NEW.`parent_com`=(NEW.`com_amt`*10/100)
       WHERE `id` = NEW.`parent_id`
  END;

ERROR:

#1064 - 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 'WHERE id = NEW.parent_id END' at line 5