CREATE TABLE [dbo].[Areas] (
  [Id] bigint  IDENTITY(1,1) NOT NULL,
  [Area] nvarchar(50) COLLATE Chinese_PRC_CI_AS  NOT NULL,
  [PId] bigint  NULL
)

WITH 
TREE AS( 
    SELECT * FROM Areas 
    WHERE id = 6  -- 要查询的子 id 
    UNION ALL 
    SELECT Areas.* FROM Areas, TREE 
    WHERE TREE.PId = Areas.Id
) 
SELECT Area FROM TREE

WITH 
TREE AS( 
    SELECT * FROM Areas 
    WHERE id = 7  -- 要查询的子 id 
    UNION ALL 
    SELECT Areas.* FROM Areas, TREE 
    WHERE TREE.Id = Areas.PId
) 
SELECT Area FROM TREE