判断null的问题
如下存储过程
create proc validateIsExist(@administratorID nchar(20),@password char(30))
as
declare @ad nchar(20)
select @ad=administratorID from administrator where administratorID=@administratorID and password=@password
print @ad
if @ad is null
return 1
else
return 0
执行改存储过程
declare @exist int
exec @exist=validateIsExist 'kaka','87096736'
print @exist
输出的结果是
kaka
0
很奇怪啊,既然已经输出了'kaka'就说明@ad不为空了,怎么@exist怎么却为0呢