【MySQL-20】关于触发器，你需要知道这些——＞定义(创建＆查看＆删除) 触发器，将变更日志插入日志表中

-- 触发器
-- 需求:通过触发器记录 user 表的数据变更日志(user_logs)，包含增加，修改 ，删除;

-- 准备工作:日志表 user_logs
create table user_logs(
  id int(11)not null auto_increment,
  operation varchar(20)not null comment '操作类型，insert/update/delete',
  operate_time datetime not null comment'操作时间',
  operate_id int(11)not null comment '操作的ID',
  operate_params varchar(500)comment '操作参数',
  primary key(`id`)
)engine=innodb default charset=utf8;

-- 查看触发器
show triggers ;
-- 删除
drop trigger tb_user_insert_trigger;
drop trigger tb_user_update_trigger;
drop trigger tb_user_delete_trigger;



-- 插入数据触发器
create trigger tb_user_insert_trigger
    after insert on tb_user for each row
begin
    insert into user_logs(id, operation, operate_time, operate_id, operate_params) 
    VALUES (null, 'insert', now(), new.id, concat('插入的数据内容为:id=',new.id,',name=',new.name, ',phone=',NEW.phone,",email='
end 
;
-- 测试：插入数指型tb_user
insert into tb_user(id, name, phone, email, profession, age, gender, status, createtime) 
VALUEs (26,"子'18809891212', 'error','teacher',23,'女','null','2022.2.21');



-- 修改数据触发器
create trigger tb_user_update_trigger
    after update on tb_user for each row
begin
    insert into user_logs(id, operation, operate_time, operate_id, operate_params)VALUES
    (null,"update',now(),new.id.
        concat('更新之前的数据:id=',old.id,',name=',old.name,'，phone=', old.phone,'，email=', old.email,',sprofession=',old.profession,
               '|更新之后的数据: id=',new.id,',name=',new.name,', phone=', NEw.phone, ', email=', NEw.email,'，profession=', NEW.profession));
end;
-- 测试：update影响多少行，就会记录几次
update tb_user set profession='会计'where id = 23;
update tb_user set profession='会计'where id <= 5;


-- 删除数搭触发器
create trigger tb_user_delete_trigger
    after delete ontbuser for each row
begin
   insert into user_logs(id, operation, operate_time, operate_id, operate_params) VALUES
(null,'delete', now(),old.id, concat('删除之前的数: id=',old.id,',name=',old.name, ', phone=', old.phone,', email=', old.email,', profession=', NEW.profession));
end: