mysql之触发器的简单应用

mysql之触发器的简单应用

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例子1：添加时触发表操作

举例的是当有进出库记录时商品库存的变化触发，例如：

CREATE TRIGGER `updateitemnum` AFTER INSERT ON `in_import`
 FOR EACH ROW if  new.import_item_status=1 then
     update in_item set item_num=item_num+new.import_item_num where item_id=new.import_item_id;   
elseif  new.import_item_status=2 then
     update in_item set item_num=item_num-new.import_item_num where item_id=new.import_item_id;  
end if

如图解释

例子2：删除时触发表操作

举例当你删除某个表数据时和这个表关联的数据表里面的对应记录也删除，例如：

CREATE TRIGGER `deleteorderdetail` BEFORE DELETE ON `in_order_master`
 FOR EACH ROW BEGIN
  DELETE FROM in_order_detail WHERE order_sn=old.order_sn; 
  DELETE FROM in_import WHERE order_sn=old.order_sn; 
END

来源：CSDN

作者：wei365456yin

链接：https://blog.csdn.net/wei365456yin/article/details/79180685