数据库之触发器

触发器是一种特殊的存储过程，下面通过触发器实现对银行存取款的操作

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1---创建触发器

2create trigger tr1 on saveinfo after

3insert 

4AS

5BEGIN

6declare        @uid    nvarchar(50)

7declare        @type int

8declare        @qian float 

9declare        @yuer   float 

10select @uid = uid,    @type=[type],@qian=[money] from saveinfo

11select @yuer= [money] from [userinfo] 

12where  uid = @uid

13if(@type = 1)     --1表示存款

14begin

15  update userinfo set [money] = [money] + @qian where  uid = @uid

16end

17else

18begin

19  if(@yuer < @qian)

20      begin

21          print '余额不足'

22      end

23  else

24      begin 

25          update userinfo set [money] = [money] - @qian where  uid = @uid

26      end

27end

28END 

29GO

30  

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