求mysql触发器

我现在需要建一个触发器，监控一个表，当这个表的某个数据发生改变的时候，我希望把改变前的一条数据插入到另外一张表里面，ID也不变

CREATE TABLE test1(id int, col1 INT);
CREATE TABLE test2(id int, col1 INT);

CREATE TRIGGER testref AFTER INSERT ON test1
  FOR EACH ROW BEGIN
  INSERT INTO test2 values (old.id,old.col1);

CREATE TRIGGER testref AFTER UPDATE ON test1
  FOR EACH ROW BEGIN
  INSERT INTO test2 values (old.id,old.col1);

CREATE TRIGGER testref AFTER DELETE ON test1
  FOR EACH ROW BEGIN
  INSERT INTO test2 values (old.id,old.col1);