从具有值和名称的数据表创建具有可变元素名称的XML [英] Create XML with variable element names from a data table with values and names

问题描述

我没有找到相关的帖子，所以我决定问。

I wasn't able to find a relevant post, so I decided to ask.

我的SQL Server数据库中有以下表格：

I have the following table in my SQL Server database:

ID       attname    value 
---------------------------------
22405543 blktradind N 
22405543 brkref     IRVTGB2X
22405543 buyamt     104650.2000 
22405543 buycurref  USD 
22405543 Buy53ref 
22405543 Buy56ref 
22405543 Buy57ref   IRVTBEBB

如何通过将FOR XML变体转换为动态基于每个消息的attname的XML结果？

How can I convert this table by using FOR XML variations to a dynamic XML result based on the "attname" that each message has?

对于上面的摘录，所需的结果将是：

For the excerpt above, the desired result would be:

<Message id=22405543>
  <blktradind>N</blktradind>
  <brkref>IRVTGB2X</brkref>
  <buyamt>104650.2000</buyamt>
  <buycurref>USD</buycurref>
  <buy53ref />
  <buy56ref />
  <buy57ref>IRVTBEBB</buy57ref>
</Message>

谢谢

推荐答案

这是不可能正常。 SQL Server不支持输出的变量列别名。但是有解决方法：

This is not possible normally. SQL Server does not support variable column aliases for your output. But there are workarounds:

这种方法有点难看，因为我通常不会喜欢通过字符串连接来创建XML。但是通过使用 SELECT FOR XML PATH 本身的值来封装这个值，这是非常稳定的禁止字符，如<>或& 。

The approach is a bit ugly, as I normally would not prefer to create XML via string concatenation. But by wrapping the value with a SELECT FOR XML PATH itself, this is even stable with forbidden characters like <> or &.

DECLARE @tbl TABLE(ID BIGINT,attname NVARCHAR(100),value NVARCHAR(100));
INSERT INTO @tbl VALUES 
 (22405543,'blktradind','N') 
,(22405543,'brkref','IRVTGB2X') 
,(22405543,'buyamt','104650.2000')  
,(22405543,'buycurref','USD')  
,(22405543,'Buy53ref',NULL) 
,(22405543,'Buy56ref',NULL) 
,(22405543,'Buy57ref','IRVTBEBB');

WITH DistinctIDs AS
(
    SELECT DISTINCT ID FROM @tbl
)
SELECT ID AS [@id]
      ,(
        SELECT CAST(N'<' + attname + N'>' + ISNULL((SELECT value AS [*] FOR XML PATH('')),N'') + N'</' + attname + N'>' AS XML)
        FROM @tbl AS tbl
        WHERE tbl.ID=DistinctIDs.ID
        FOR XML PATH(''),TYPE
       )
FROM DistinctIDs
FOR XML PATH('Message')

结果

<Message id="22405543">
  <blktradind>N</blktradind>
  <brkref>IRVTGB2X</brkref>
  <buyamt>104650.2000</buyamt>
  <buycurref>USD</buycurref>
  <Buy53ref />
  <Buy56ref />
  <Buy57ref>IRVTBEBB</Buy57ref>
</Message>

动态SQL

动态完整语句，并使用 EXEC（@cmd）来执行它。这样的一个例子：

dynamic SQL

You could build the full statement dynamically and use EXEC(@cmd) to execute it. Something like this:

（注意!! ： SELECT TOP 1 该ID不适合实际数据！）

(Attention!!: The SELECT TOP 1 to get the ID is not appropriate for actual data!)

DECLARE  @cmd NVARCHAR(MAX)=
(
    SELECT 'SELECT ''' + CAST((SELECT TOP 1 ID FROM @tbl) AS NVARCHAR(100)) + ''' AS [@id] ' 
    + (
    SELECT ',''' + ISNULL(value,'') + ''' AS [' + attname + ']'
    FROM  @tbl
    FOR XML PATH('')
    )
    + ' FOR XML PATH(''Message'')'
);
EXEC(@cmd)

这篇关于从具有值和名称的数据表创建具有可变元素名称的XML的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！