update bankcard set maney = maney -5000 where id = 1
//测试用的sql语句
CREATE TRIGGER 触发器名称 ON [dbo].[bankCard]
FOR INSERT, UPDATE, DELETE
AS
if update(maney) //列名
declare @firstManey int
declare @secondManey int
declare @fristCardID int
declare @secondCardID int
select @firstManey = maney from inserted
select @secondManey = maney from deleted
select @fristCardID = CardID from inserted
select @secondCardID = CardID from deleted
update bankCard set maney =( maney - (@secondManey - @firstManey)) where CardID = @secondCardID 


数据库
| CardID | 主键 int | 卡号 |
| maney | int | 金额 |
on 后面是标名字 update 动作 inserted是update语句执行前的虚拟表 deleted是update语句修改以后的虚拟表