SQL对select语句返回多条记录给变量赋值时如何处理?
SQL对select语句返回多条记录给变量赋值时如何处理?
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。
答:(tb为表名) select * from tb where id in(select max(id) from tb group by name) 选择ID最...详情>>