从 XML 节点解析 TSQL

Question

此 XML 来自公共金库。 SQL Server 似乎认为它不是 XML？我的结果表明 XLT 方法只能涉及列类型 XML。这个来自金库的结果集真的是 XML 吗？

如何将其解析为 SQL 表？

treasury daily market yield

DECLARE @XML NVARCHAR(MAX)
SELECT @XML = 
'<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<feed xml:base="http://data.treasury.gov/Feed.svc/" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom">
  <title type="text">DailyTreasuryYieldCurveRateData</title>
  <id>http://data.treasury.gov/feed.svc/DailyTreasuryYieldCurveRateData</id>
  <updated>2020-07-14T05:40:26Z</updated>
  <link rel="self" title="DailyTreasuryYieldCurveRateData" href="DailyTreasuryYieldCurveRateData"/>
  <entry>
    <id>http://data.treasury.gov/Feed.svc/DailyTreasuryYieldCurveRateData(7633)</id>
    <title type="text"/>
    <updated>2020-07-14T05:40:26Z</updated>
    <author>
      <name/>
    </author>
    <link rel="edit" title="DailyTreasuryYieldCurveRateDatum" href="DailyTreasuryYieldCurveRateData(7633)"/>
    <category term="TreasuryDataWarehouseModel.DailyTreasuryYieldCurveRateDatum" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme"/>
    <content type="application/xml">
      <m:properties>
        <d:Id m:type="Edm.Int32">7633</d:Id>
        <d:NEW_DATE m:type="Edm.DateTime">2020-07-01T00:00:00</d:NEW_DATE>
        <d:BC_1MONTH m:type="Edm.Double">0.12</d:BC_1MONTH>
        <d:BC_2MONTH m:type="Edm.Double">0.12</d:BC_2MONTH>
        <d:BC_3MONTH m:type="Edm.Double">0.14</d:BC_3MONTH>
        <d:BC_6MONTH m:type="Edm.Double">0.17</d:BC_6MONTH>
        <d:BC_1YEAR m:type="Edm.Double">0.16</d:BC_1YEAR>
        <d:BC_2YEAR m:type="Edm.Double">0.17</d:BC_2YEAR>
        <d:BC_3YEAR m:type="Edm.Double">0.19</d:BC_3YEAR>
        <d:BC_5YEAR m:type="Edm.Double">0.31</d:BC_5YEAR>
        <d:BC_7YEAR m:type="Edm.Double">0.52</d:BC_7YEAR>
        <d:BC_10YEAR m:type="Edm.Double">0.69</d:BC_10YEAR>
        <d:BC_20YEAR m:type="Edm.Double">1.2</d:BC_20YEAR>
        <d:BC_30YEAR m:type="Edm.Double">1.43</d:BC_30YEAR>
        <d:BC_30YEARDISPLAY m:type="Edm.Double">1.43</d:BC_30YEARDISPLAY>
      </m:properties>
    </content>
  </entry>
</feed>'
   
SELECT  b.value('@d:Id', 'varchar(28)') as d_id
       ,b.value('@d:BC_30YEAR', 'double') as d_BC_30YEAR
  FROM @XML.nodes('feed/entry/content type/m:properties/') as a(b)

Answer 1

首先，将@XML 定义为XML 类型：

DECLARE @XML XML;

然后：您需要定义相关的 XML 命名空间！

试试这个sn-p的代码：

-- define XML namespaces!
;WITH XMLNAMESPACES(DEFAULT 'http://www.w3.org/2005/Atom', 
                    'http://schemas.microsoft.com/ado/2007/08/dataservices/metadata' AS m,
                    'http://schemas.microsoft.com/ado/2007/08/dataservices' AS d)
SELECT  
    b.value('(d:Id)[1]', 'varchar(28)') as d_id,
    b.value('(d:BC_30YEAR)[1]', 'decimal(20,2)') as d_BC_30YEAR
FROM 
    @XML.nodes('feed/entry/content/m:properties') as a(b)

这将返回以下值：

我所做的修复：

FROM @XML.nodes('feed/entry/content type/m:properties/') as a(b)  
                            ^^^^^^^^^^^^

错误的节点名称 - 节点是 <content>（不是“内容类型”） - type 只是节点上的一个属性，与此 XPath 无关。

SELECT b.value('@d:Id', 'varchar(28)') as d_id  
                ^^^^^^

您确实想要选择 XML 元素（节点）d:Id - 不是属性 - @d:Id 中的 @ 表示属性！

b.value('@d:BC_30YEAR', 'double') as d_BC_30YEAR  
                        ^^^^^^^^^

您需要使用正确的 T-SQL 数据类型 - 例如 decimal(20,2) - 而不是“double” 这里....