declare @user nvarchar(20)

select @user='user1'

use countme

/*判断用户是否存在*/

declare @userweek int

select @userweek=[week] from base where userid=@user

select @@rowcount

if @@rowcount=0

return

select @userweek

最后的@userweek打印出来的结果就是记录用户名为user1的week字段的值

而当我们用下面的语句选择所有记录时(没有where限制)

declare @user nvarchar(20)

select @user='user1'

use countme

/*判断用户是否存在*/

declare @userweek int

select @userweek=[week] from base

select @@rowcount

if @@rowcount=0

return

select @userweek

最后@userweek打印出来的值是返回的所有记录中排名最后一条记录的week字段值