CREATE FUNCTION 存儲(chǔ)函數(shù)名稱(chēng) ([ 參數(shù)列表 ])
RETURNS type [characteristic ...]
BEGIN
-- SQL語(yǔ)句
RETURN ...;
END ;

create function fun1(n int)
returns int deterministic
begin
        declare total int default 0;
        while n>0 do
            set total := total + n;
            set n := n - 1;
        end while;
        return total;
end;
select fun1(50);

CREATE TRIGGER trigger_name
BEFORE/AFTER INSERT/UPDATE/DELETE
ON tbl_name FOR EACH ROW -- 行級(jí)觸發(fā)器
BEGIN
trigger_stmt ;
END;

SHOW TRIGGERS ;

DROP TRIGGER [schema_name.]trigger_name ; -- 如果沒(méi)有指定 schema_name，默認(rèn)為當(dāng)前數(shù)據(jù)庫(kù) 。

-- 準(zhǔn)備工作 : 日志表 user_logs
create table user_logs(
id int(11) not null auto_increment,
operation varchar(20) not null comment '操作類(lèi)型, insert/update/delete',
operate_time datetime not null comment '操作時(shí)間',
operate_id int(11) not null comment '操作的ID',
operate_params varchar(500) comment '操作參數(shù)',
primary key(`id`)
)engine=innodb default charset=utf8;

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('插入的數(shù)據(jù)內(nèi)容為:
id=',new.id,',name=',new.name, ', phone=', NEW.phone, ', email=', NEW.email, ',
profession=', NEW.profession));
end;

-- 查看
show triggers ;
-- 插入數(shù)據(jù)到tb_user
insert into tb_user(id, name, phone, email, profession, age, gender, status,
createtime) VALUES (26,'三皇子','18809091212','erhuangzi@163.com','軟件工
程',23,'1','1',now());

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('更新之前的數(shù)據(jù): id=',old.id,',name=',old.name, ', phone=',
old.phone, ', email=', old.email, ', profession=', old.profession,
' | 更新之后的數(shù)據(jù): id=',new.id,',name=',new.name, ', phone=',
NEW.phone, ', email=', NEW.email, ', profession=', NEW.profession));
end;

-- 查看
show triggers ;
-- 更新
update tb_user set profession = '會(huì)計(jì)' where id = 23;
update tb_user set profession = '會(huì)計(jì)' where id <= 5;

create trigger tb_user_delete_trigger
after delete on tb_user for each row
begin
insert into user_logs(id, operation, operate_time, operate_id, operate_params)
VALUES
(null, 'delete', now(), old.id,
concat('刪除之前的數(shù)據(jù): id=',old.id,',name=',old.name, ', phone=',
old.phone, ', email=', old.email, ', profession=', old.profession));
end;

-- 查看
show triggers ;
-- 刪除數(shù)據(jù)
delete from tb_user where id = 26;