存储过程的问题

[hbzx]

CREATE procedure GetLastRec
@a int, @b int AS
select * from
(
select * from (select top @a employeeid,title from employees order by title) as a --5行
union all
select * from (select top @b employeeid,title from employees order by title) as b --7行
)
a
group by employeeid,title having count(employeeID)=1 order by employeeid
GO


提示5,7行的 @a @b有错 改成数字就行

还有有些变量是@@开头的是什么意思 如@@TABLE varchar(30) = 'sys%'