sql 递归算法

Declare @Id Int
Set @Id = 0;    ---在此修改父节点
 
With RootNodeCTE
As
(
Select Id,ParentId,[TName],cast(1 as int) as [level] From [TreeTable] Where ParentId In (@Id)
Union All
Select [TreeTable].Id,[TreeTable].ParentId,[TreeTable].[TName],RootNodeCTE.[level]+1 as [level] From RootNodeCTE
Inner Join [TreeTable]
On RootNodeCTE.Id = [TreeTable].ParentId
) 
 
SELECT * FROM RootNodeCTE