SQL Server中XML列的反向順序

Question

在SQL Server表中，我有一個XML列，其中狀態發生（首先是最早的，最後一個當前狀態）。

我必須編寫一個返回狀態的存儲過程：最新的第一個，最舊的最後一個。

這是我寫的：價值

ALTER PROCEDURE [dbo].[GetDeliveryStatus] 
    @invoiceID nvarchar(255) 
AS 
BEGIN 
    SET NOCOUNT ON; 

    DECLARE @xml xml 
    SET @xml = (SELECT statusXML 
       FROM Purchase 
       WHERE invoiceID = @invoiceID) 

    SELECT 
     t.n.value('text()[1]', 'nvarchar(50)') as DeliveryStatus 
    FROM 
     @xml.nodes('/statuses/status') as t(n) 
    ORDER BY 
     DeliveryStatus DESC 
END 

例如，在statusXML列：

<statuses> 
    <status>A</status> 
    <status>B</status> 
    <status>A</status> 
    <status>B</status> 
    <status>C</status> 
</statuses> 

我想程序返回的：

C 
B 
A 
B 
A 

與ORDER BY .... DESC它的回報ALPHABETIC逆轉（C B B A A）

我應該如何糾正我的程序？

Answer 1

沒有必要首先聲明一個變量。你可以（你應該！）直接從表列中讀取所需的值。最好成績是內嵌表值函數（而不是SP只是閱讀東西......）

• 更好的性能
• inlineable
• 您可以一次
• 集查詢許多InvoiceIDs - 基

試試這個（我放棄模擬表 - 真正的數據！）：

CREATE TABLE Purchase(ID INT IDENTITY,statusXML XML, InvocieID INT, OtherValues VARCHAR(100)); 
INSERT INTO Purchase VALUES('<statuses> 
    <status>A</status> 
    <status>B</status> 
    <status>A</status> 
    <status>B</status> 
    <status>C</status> 
</statuses>',100,'Other values of your row'); 
GO 

WITH NumberedStatus AS 
(
    SELECT ID 
      ,InvocieID 
      , ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS Nr 
      ,stat.value('.','nvarchar(max)') AS [Status] 
      ,OtherValues 
    FROM Purchase 
    CROSS APPLY statusXML.nodes('/statuses/status') AS A(stat) 
    WHERE InvocieID=100 
) 
SELECT * 
FROM NumberedStatus 
ORDER BY Nr DESC 
GO 
--Clean-Up 
--DROP TABLE Purchase; 

結果

+---+-----+---+---+--------------------------+ 
| 1 | 100 | 5 | C | Other values of your row | 
+---+-----+---+---+--------------------------+ 
| 1 | 100 | 4 | B | Other values of your row | 
+---+-----+---+---+--------------------------+ 
| 1 | 100 | 3 | A | Other values of your row | 
+---+-----+---+---+--------------------------+ 
| 1 | 100 | 2 | B | Other values of your row | 
+---+-----+---+---+--------------------------+ 
| 1 | 100 | 1 | A | Other values of your row | 
+---+-----+---+---+--------------------------+ 

Answer 2

根據現有的順序爲節點創建一個序列，然後將其逆轉。

WITH [x] AS (
    SELECT 
     t.n.value('text()[1]', 'nvarchar(50)') as DeliveryStatus 
     ,ROW_NUMBER() OVER (ORDER BY t.n.value('..', 'NVARCHAR(100)')) AS [Order] 
    FROM 
     @xml.nodes('/statuses/status') as t(n) 
) 
    SELECT 
     DeliveryStatus 
    FROM [x] 
    ORDER BY [x].[Order] DESC 

...結果...

DeliveryStatus 
C 
B 
A 
B 
A