Trường XML - Truy vấn

Đây là ans với toán tử xquery ->

declare @xmldata xml
    set @xmldata = 
    '<DynamicProfile xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/WinTest">
  <AllData xmlns:d2p1="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
    <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MyFirstKey</d2p1:Key>
      <d2p1:Value>MyFirstValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>
    <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MySecondKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>
    <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MySecondKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>  <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MyFirstKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>  <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MyFirstKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>  <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MySecondKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>  <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MySecondKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>  <d2p1:KeyValueOfstringstring>
      <d2p1:Key>MyFirstKey</d2p1:Key>
      <d2p1:Value>MySecondValue</d2p1:Value>
    </d2p1:KeyValueOfstringstring>  </AllData>
</DynamicProfile>'

;WITH XMLNAMESPACES 
(
    DEFAULT 'http://schemas.datacontract.org/2004/07/WinTest',
    'http://schemas.microsoft.com/2003/10/Serialization/Arrays' as d2p1
)
SELECT  x.c.value('(d2p1:Key)[1]', 'varchar(100)') as key3, x.c.value('(d2p1:Value)[1]', 'varchar(100)') as value
FROM @xmldata.nodes('/DynamicProfile/AllData/d2p1:KeyValueOfstringstring') x(c) where x.c.value('(d2p1:Key)[1]', 'varchar(100)') = 'MySecondKey'