查詢，選擇和最高相結合，從表中

Question

下限值我們有我們的SQL Server 2012的

表A（數據）以下表格：

ID, Description 
--------------- 
1 , Bla 1 
2 , Bla 2 
3 , Bla 3 

表P中（數據）：

ID, ParentID, Name 
------------------ 
1 , NULL , AAA 
2 , 3  , CCC 
3 , 1  , XXX 

表X（外鍵A_ID到A.ID和P_ID到P.ID）：

ID, A_ID, P_ID 
-------------- 
1 , 1 , 1 
2 , 1 , 2 
3 , 2 , 1 
4 , 2 , 2 
5 , 2 , 3 
6 , 3 , 1 

問題：

我們需要一個查詢是這樣的：

SELECT ... 
WHERE A_ID = 1 

應該返回這個結果：

ID, Name, Subname 
----------------- 
2 , AAA , CCC 

• 名稱需要包含來自表P的最高名稱，即沒有ParentID的名稱。
• 子表名稱需要包含表P中最底部的名稱，表中ID仍然存在於表X.
• ID需要包含來自表X的ID，其中P_ID是最底層子代的ID。

又如：

SELECT ... 
WHERE A_ID = 2 

應該返回這樣的結果：

ID, Name, Subname 
----------------- 
4 , AAA , CCC 

而且

SELECT ... 
WHERE A_ID = 3 

應該返回這樣的結果：

ID, Name, Subname 
----------------- 
6 , AAA , NULL 

我們已經嘗試了各種查詢，但有些僅適用於'where A_ID = 1'而不適用於'where A_ID = 2'。爲了從P中選擇最低級別的孩子，我們查看了'How to select lowest level in hierarchy form table帖子'，這對於我們正在查找的查詢可能會派上用場。

單個查詢會很好，但我們也會接受存儲過程。

提前致謝！

信息

• 所有表中的ID列是主鍵
• 在任何給定表中的ID的列可以被改變爲在採樣數據的任何其它值，考慮到初級而和外鍵約束。 （例如，將P.ID'2'更改爲'4'也會導致X.P_ID的'2'更改爲'4'。）這表明ID不一定按順序排列。
• P.Name列中的值可以是任何非空值。
• 表P可以有多個ParentId設置爲null的行。

樣本數據 從@NEER

DECLARE @A TABLE (ID INT, DESCRIPTION NVARCHAR(10)) 
INSERT INTO @A 
VALUES 
(1 , 'Bla 1'), 
(2 , 'Bla 2'), 
(3 , 'Bla 3') 


DECLARE @P TABLE (ID INT, ParentID INT, Name NVARCHAR(10)) 
INSERT INTO @P 
VALUES 
(1 , NULL , 'AAA'), 
(2 , 3  , 'CCC'), 
(3 , 1  , 'XXX') 


DECLARE @X TABLE (ID INT,A_ID INT,P_ID INT) 
INSERT INTO @X 
VALUES 
(1 , 1 , 1), 
(2 , 1 , 2), 
(3 , 2 , 1), 
(4 , 2 , 2), 
(5 , 2 , 3), 
(6 , 3 , 1) 

Answer 1

與下面的查詢嘗試服用。我認爲Table A不需要獲得所需的結果。

SELECT TOP 1 First_VALUE(x.ID) OVER(ORDER BY x.ID desc) ID 
      ,First_VALUE(Name) OVER(ORDER BY p.ID) Name 
      ,CASE WHEN First_VALUE(Name) OVER(ORDER BY p.ID) = First_VALUE(Name) OVER(ORDER BY p.ID desc) THEN NULL 
        ELSE First_VALUE(Name) OVER(ORDER BY p.ID desc) END SubName 
FROM [table P] p 
JOIN [table X] x 
    ON p.ID=x.[P_ID] 
WHERE x.[A_ID]=3 

Answer 2

嘗試以下查詢

DECLARE @TableA AS TABLE (ID INT,Des NVARCHAR(MAX)); 
Insert Into @TableA VALUES(1,'Bal 1'); Insert Into @TableA VALUES(2,'Bal 2'); Insert Into @TableA VALUES(3,'Bal 3'); 
DECLARE @TableP AS TABLE (ID INT,ParentID INT,Name NVARCHAR(MAX)); 
Insert Into @TableP VALUES(1,Null,'AAA'); Insert Into @TableP VALUES(2,1,'BBB'); Insert Into @TableP VALUES(3,2,'CCC'); 
DECLARE @TableX AS TABLE (ID INT,A_ID INT,P_ID INT); 
Insert Into @TableX Values(1,1,1); Insert Into @TableX Values(2,1,2); Insert Into @TableX Values(3,2,1); Insert Into @TableX Values(4,2,3); Insert Into @TableX Values(5,3,1); 

Select Top 1 X.ID,(Select top 1 Name from @TableP Where ParentID is null) Name,P.Name as SubName 
from @TableX as X 
Inner Join @TableP as P On P.ID=x.P_ID And P.ParentID IS Not Null 
Where A_ID=1 
Order by X.ID Desc 

Select Top 1 X.ID,(Select top 1 Name from @TableP Where ParentID is null) Name,P.Name as SubName 
from @TableX as X 
Left Join @TableP as P On P.ID=x.P_ID And P.ParentID IS Not Null 
Where A_ID=2 
Order by X.ID Desc 

Select Top 1 X.ID,(Select top 1 Name from @TableP Where ParentID is null) Name,P.Name as SubName 
from @TableX as X 
Left Join @TableP as P On P.ID=x.P_ID And P.ParentID IS Not Null 
Where A_ID=3 
Order by X.ID Desc 

Answer 3

您可以使用Recursive CTE爲如下：

DECLARE @A TABLE (ID INT, DESCRIPTION NVARCHAR(10)) 
INSERT INTO @A 
VALUES 
(1 , 'Bla 1'), 
(2 , 'Bla 2'), 
(3 , 'Bla 3') 


DECLARE @P TABLE (ID INT, ParentID INT, Name NVARCHAR(10)) 
INSERT INTO @P 
VALUES 
(1 , NULL , 'AAA'), 
(2 , 3  , 'CCC'), 
(3 , 1  , 'XXX') 


DECLARE @X TABLE (ID INT,A_ID INT,P_ID INT) 
INSERT INTO @X 
VALUES 
(1 , 1 , 1), 
(2 , 1 , 2), 
(3 , 2 , 1), 
(4 , 2 , 2), 
(5 , 2 , 3), 
(6 , 3 , 1) 

DECLARE @A_ID INT = 2 

;WITH Parents 
AS 
(
    SELECT 
     P.ID, P.ParentID, P.Name 
    FROM @P P WHERE P.ParentID IS NULL 
    UNION ALL 
    SELECT 
     P.ID, Parent.ID, Parent.Name 
    FROM 
     @P P INNER JOIN 
     Parents Parent ON P.ParentID = Parent.ID 
), Temp 
AS 
(
    SELECT 
     X.ID, 
     Parent.Name Name, 
     IIF(P.ParentID IS NULL, NULL, P.Name) SubName  
    FROM 
     @A A INNER JOIN 
     @X X ON X.A_ID = A.ID INNER JOIN 
     @P P ON X.P_ID = P.ID LEFT JOIN 
     Parents Parent ON P.ParentID = Parent.ID OR (P.ParentID IS NULL AND P.ID = Parent.ID) 
    WHERE 
     A.ID = @A_ID 
), MainTable 
AS 
(
    SELECT 
     Temp.ID , 
     Temp.Name , 
     Temp.SubName, 
     COUNT(Temp.ID) OVER (PARTITION BY Temp.Name ORDER BY (SELECT NULL)) CountOfRowByParent 
    FROM 
     Temp 
) 


SELECT 
    MainTable.ID , 
    MainTable.Name , 
    MainTable.SubName  
FROM 
    MainTable 
WHERE 
    (
     MainTable.CountOfRowByParent > 1 AND 
     MainTable.SubName IS NOT NULL 
    ) OR 
    MainTable.CountOfRowByParent = 1 

結果爲2：

ID Name SubName 
4 AAA  CCC 
5 AAA  XXX 

Answer 4

你可以嘗試以下

with report as (
    select max(x.ID) as ID, min(x.P_ID) as MinP, max(x.P_ID) as MaxP 
    from X x 
    where x.A_ID = 1 -- <-- here you can change the value 
) 

select r.ID, 
     mn.Name as Name, 
     case when r.MinP = r.MaxP then null else mx.Name end as Subname 
from report r 
inner join P mn on mn.ID = r.MinP 
inner join P mx on mx.ID = r.MaxP 

希望這將幫助你

Answer 5

與GROUP試試看BY：

SELECT x.a_id, max(x.id) AS id, min(p.name) AS name, 
CASE WHEN max(p.name) = min(p.name) THEN NULL 
ELSE max(p.name) END AS subname 
FROM p INNER JOIN x 
ON p.id = x.p_id 
GROUP BY x.a_id 
HAVING x.a_id = 1 

與更新的樣本數據仍然有效。測試在這裏：http://sqlfiddle.com/#!9/99597f/1