使用属性解析 XML

Question

给定一个具有以下结构的 XML：

<someStructure>
    <Tag1 Qualifier = "QQ" Name = "Name">
        <Tag2 Code = "CD" Name = "SomeName">
            <Tag3 Qualifier = "QW" Number = "22"/>
        </Tag2>
    </Tag1>
    <Tag1 Qualifier = "NN" Name = ""/>
    <Tag1 Qualifier = "QE" Name = "Name2">
        <Tag2 Code = "CD" Name = "SomeName2">
            <Tag3 Qualifier = "QW" Number = "22"/>
        </Tag2>
    </Tag1>
</someStructure>

是否可以通过 1 个查询来解析结果？

我可以用 XML.nodes 解析每一行并将其作为 value() 但我无法获取子节点的结果。

我想做这样的事情

SELECT b.value('@Qualifier', 'nvarchar(max)'),b.value('@Name', 'nvarchar(max)'),
b.value('/Tag2/@Code', 'nvarchar(max)'),b.value('/Tag2/@Name', 'nvarchar(max)'),
b.value('/Tag2/Tag3/@Qualifier', 'nvarchar(max)'),b.value('/Tag2/Tag3/@Number', 'nvarchar(max)')
FROM @xml.nodes('/someStructure/Tag1') as a(b)

但是我收到这个错误：

Msg 2389, Level 16, State 1, Procedure spParse_XML, Line 96 [Batch Start Line 0] XQuery [value()]: 'value()' requires a singleton (or empty sequence), found operand of type 'xdt:untypedAtomic *'

我已经设法通过解析不同查询中的每一行来获得预期值，但我确信这不是最好的方法..

SELECT b.value('@Qualifier', 'nvarchar(max)'),b.value('@Name', 'nvarchar(max)')
FROM @xml.nodes('/someStructure/Tag1') as a(b)

SELECT b.value('@Code', 'nvarchar(max)'),b.value('@Name', 'nvarchar(max)')
FROM @xml.nodes('/someStructure/Tag1/Tag2') as a(b)
    
SELECT b.value('@Qualifier', 'nvarchar(max)'),b.value('@Name', 'nvarchar(max)')
FROM @xml.nodes('/someStructure/Tag1/Tag2/Tag3') as a(b)

Answer 1

正如错误告诉您的那样，您还没有定义单例，它定义了值来自哪个编号节点。您很可能只想要第一个节点。我还更改了你的数据类型，因为我怀疑你的值最多可以有 10 亿个字符（尽管我对大多数使用 nvarchar(2)，这可能不够长在所有地方）。

这给出了如下内容：

DECLARE @XML xml = '<someStructure>
    <Tag1 Qualifier = "QQ" Name = "Name">
        <Tag2 Code = "CD" Name = "SomeName">
            <Tag3 Qualifier = "QW" Number = "22"/>
        </Tag2>
    </Tag1>
    <Tag1 Qualifier = "NN" Name = ""/>
    <Tag1 Qualifier = "QE" Name = "Name2">
        <Tag2 Code = "CD" Name = "SomeName2">
            <Tag3 Qualifier = "QW" Number = "22"/>
        </Tag2>
    </Tag1>
</someStructure>';

SELECT sS.T1.value('(@Qualifier)[1]','nvarchar(2)') AS Tag1Qualifier, --Does this "need" to be up to 1 billion characters long?
       sS.T1.value('(@Name)[1]','nvarchar(20)') AS Tag1Name, --Does this "need" to be up to 1 billion characters long?
       sS.T1.value('(Tag2/@Code)[1]','nvarchar(2)') AS Tag2Code, --Does this "need" to be up to 1 billion characters long?
       sS.T1.value('(Tag2/@Name)[1]','nvarchar(20)') AS Tag2Name, --Does this "need" to be up to 1 billion characters long?
       sS.T1.value('(Tag2/Tag3/@Qualifier)[1]','nvarchar(2)') AS Tag3Qualifier, --Does this "need" to be up to 1 billion characters long?
       sS.T1.value('(Tag2/Tag3/@Number)[1]','int') AS Tag3Number --Does this "need" to be up to 1 billion characters long?
FROM (VALUES(@XML))V(X)
     CROSS APPLY V.X.nodes('/someStructure/Tag1') sS(T1);

使用属性解析 XML

Parse XML with Attributes

xml

sql-server

xml-parsing