SQL CROSS APPLY 用法

有两个表,分类表,和文件表

两个表的关联地段是分类ID

要求,查询每个分类表下面最后更新的三条文件表数据

select * from Category as c
cross apply 
(select  top 3 * from FileCategory as rc where c.Id = CategoryId order by rc.UpdateTime desc) as rc