Mysql触发器在两个连接的表上插入

Question

我有 3 个 mysql 表：

user_followers 有列 id,user_id 通知 有列 id,user_id notification_object 有列 notification_id ，类型

在 user_followers 上插入时我想插入

user_id=通知中的New.user_id

然后使用刚刚插入的通知的id

notification_object.type = "2" and notification_object.notification_id = 刚刚在通知表中插入了 id

现在的问题是如何找到通知表的 id：

DELIMITER //


CREATE TRIGGER follow_notification AFTER INSERT ON user_friends
FOR EACH ROW 
Begin
insert into notification(user_id) values(New.user_id);
insert into notification_object(notification_id,type) values(????,"2");

End

//

Answer 1

如果notifications.id 是自动递增的，mysql 包含一个函数last_insert_id()，它将返回（with caveats）最后插入的id。

DELIMITER //

CREATE TRIGGER follow_notification AFTER INSERT ON user_friends
FOR EACH ROW 
Begin
  declare v_notification_id INT;
  insert into notification(user_id) values(New.user_id);
  /* set a variable to the last id inserted to the db */
  set v_notification_id=(select last_insert_id());
  /* use the variable in the next insert */
  insert into notification_object(notification_id,type) values(v_notification_id,"2");

End//