MySql中的存储过程和触发器笔记

#表结构
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(100) DEFAULT NULL,
  `user_type` tinyint(4) DEFAULT NULL,
  `user_password` varchar(50) DEFAULT NULL,
  `user_phone` varchar(12) DEFAULT NULL COMMENT,
  `user_pic` varchar(100) DEFAULT NULL COMMENT,
  `is_leave` tinyint(4) DEFAULT NULL COMMENT,
  `remark` varchar(500) DEFAULT NULL COMMENT,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COMMENT='用户表';
#===============创建一个简单的存储过程===============
create procedure helloworld()
begin 
	select * from `user`;
	select 'Hello World!' from dual;
end;
#调用存储过程
call helloworld();
#删除存储过程
drop procedure if exists helloworld;

#===============简单的存储过程（带参数）===============
create procedure selectUserById(in p3 int)
begin 
	select * from `user` where id = p3;
end;
#调用存储过程
call selectUserById(2);
#删除存储过程
drop procedure if exists selectUserById;

#===============简单的存储过程（使用游标，带参数）===============
create procedure selectUserByIdWithCursor(in p3 int)
begin 
	#申明游标的值
	declare not_found int default 0;
	#申明变量
	declare _id int;
	declare name varchar(200) default '';
	declare type int;
	declare password varchar(200);
	declare names varchar(200) default '';
	#申明游标
	declare cursorName cursor for select id,user_name,user_type,user_password from `user` where id = p3;
	#对游标的控制处理，当没有找到为false
	declare continue handler for not found set not_found=0;
	#打开游标
	open cursorName;
		#循环取值（使用loop循环）
		_loop:loop 
			fetch cursorName into _id,name,type,password;
			if not_found=1 then leave _loop;
			end if;
			#输出
			select CONCAT(_id,name,type,password);
		end loop _loop;
	#关闭游标
	close cursorName;
end;
#调用存储过程
call selectUserByIdWithCursor(0);
#删除存储过程
drop procedure if exists selectUserByIdWithCursor;
#===============简单的触发器（）===============
create trigger checkUserType
before insert 
on `user`
for each row 
begin 
	#如果插入用户的类型错误
	if new.user_type<0 then signal sqlstate 'HY000' set message_text = '手动抛出异常' ; 
end if;
end;
#删除触发器
drop trigger if exists checkUserType;