Mysql基础第二十八天,使用触发器

Posted 2021-08-27 2019ab

触发器

创建触发器时,需要给出4条信息

delimiter // 
create trigger trg_order_inser after insert on orders
  for each row
begin
  insert into order_log(o_date,order_num) values (now(),new.order.num);
end;
//

使用触发器

create table order_log(id int auto_increment primary key,o_date datetime,order_num int);
drop trigger trg_order_inser;
create trigger trg_order_inser after insert on orders
  for each row
begin
  insert into order_log(o_date,order_num,dml_type) values (now(),new.order.num,'insert');
end;

insert into orders (order_date,cust_id) values('2021-1-1',10005);

删除触发器

create trigger trg_order_delete after delete on orders
  for each row
begin
  insert into order_log(o_date,order_num,dml_type) values (now(),old.order.num,'delete');
end;
delete from orders where order_num = 2010;

更新触发器

create trigger trg_order_update after update on orders
  for each row
begin
  insert into order_log(o_date,order_num,dml_type) values (now(),old.order.num,'update');
end; // update 操作

delimiter  //
create trigger trg_products_update before update on product
  for each row
begin 
  if new.prod_price>old.prod_price * 1.2 then 
    set new.prod_price = old.prod_price *1.2;
  end if;
end;
//