SQL Server 樹形表非循環遞歸查詢的實例詳解

很多人可能想要查詢整個樹形表關聯的內容都會通過循環遞歸來查...事實上在微軟在SQL2005或以上版本就能用別的語法進行查詢，下面是示例。

--通過子節點查詢父節點
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 6 -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
) 
SELECT Area FROM TREE
--通過父節點查詢子節點
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 7 -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.Id = Areas.PId
) 
SELECT Area FROM TREE

通過子節點查詢父節點查詢結果為：

修改代碼為

--通過子節點查詢父節點
declare @area varchar(8000);
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = 6 -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
)
select @area=isnull(@area,'')+Area from Tree order by id 
select Area= @area

則結果為：中國北京市豐台區

根據以上可以將這段代碼封裝為一個存儲過程

-----存儲過程，遞歸獲取樹形地區表字符串
if exists (select * from sysobjects where name='SP_GetAreaStr')
drop proc SP_GetAreaStr
go
create procedure SP_GetAreaStr 
@id int
as
declare @area varchar(8000)
begin
WITH 
TREE AS( 
SELECT * FROM Areas 
WHERE id = @id -- 要查詢的子 id 
UNION ALL 
SELECT Areas.* FROM Areas, TREE 
WHERE TREE.PId = Areas.Id
)
select @area=isnull(@area,'')+Area from Tree order by id 
select Area= @area
end 
go
--exec sp_helptext 'SP_GetAreaStr'
--go
exec SP_GetAreaStr 28
go

查詢結果：中國安徽省宿州市靈璧縣

所用表結構：

部分數據：

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