mysql触发器的插入操作，如何进行判断
例如，创建触发器：
DELIMITER $$

CREATE
  /*[DEFINER = { user | CURRENT_USER }]*/
  TRIGGER test.t_afterinsert_on_test AFTER INSERT
  ON test.t_user
  FOR EACH ROW BEGIN
INSERT INTO test2.t_user VALUES(new.id, new.name, new.password);
  END $$
   
DELIMITER ;

在执行INSERT INTO test2.t_user VALUES(new.id, new.name, new.password);之前需要进行判断id是否存在（类似于:if(select * from t_user where id = new.id) == 0,之类的判断），不存在，则执行，因为是两个表。

如何实现？求解，谢谢

------解决方案--------------------
FOR EACH ROW BEGIN
if not exists (select * from t_user where id = new.id) then
INSERT INTO test2.t_user VALUES(new.id, new.name, new.password);
end if;
END $$
 
------解决方案--------------------

探讨

FOR EACH ROW BEGIN
if not exists (select * from t_user where id = new.id) then
INSERT INTO test2.t_user VALUES(new.id, new.name, new.password);
end if;
END $$

------解决方案--------------------
CREATE
/*[DEFINER = { user | CURRENT_USER }]*/
TRIGGER test.t_afterinsert_on_test AFTER INSERT
ON test.t_user
INSERT INTO test2.t_user VALUES(new.id, new.name, new.password) on duplicate update name=new.name;