TSQL CTE 查出所有子类ID

[Category]  表

ID Name ParentID
1 新闻 0
2 视频 1
3 资讯 1
4 图文 1
5 最新 3
6 经典 3

declare @ParentID int ;
set @ParentID = 1;

With CTE(ID,ParentID) as
(
	select ID,ParentID from [Category] where ParentID = @ParentID
	union all
	select TB.ID,TB.ParentID from [Category] as TB,CTE where TB.ParentID = CTE.ID
)


select ID from CTE

结果：

ID
2
3
4
5
6