SQL Server Query XML in Nvarchar(max) Field?

I have XML stored in an nvarchar(max) field. I realize there is an XML data type, but in this case it开发者_如何学JAVA is not stored that way. Let's say the XML is structured like the following:

<root>
<hdr>
  <name>aj</name>
</hdr>
<dtls>
  <dtl>
    <price>1</price>
  </dtl>
  <dtl>
    <price>7</price>
  </dtl>
  <dtl>
    <price>3</price>
  </dtl>
</dtls>
</root>

What I am trying to do is get the count of detail (dtl) nodes that exist for record. I am sure this is possible with xpath/xquery, I am just not exactly sure how.

Try this:

SELECT CAST(<YOUR_XML_COLUMN> AS XML).query('count(//dtl)')
  FROM <YOUR_TABLE>

e.g:

DECLARE @x NVARCHAR(MAX)
SET @x = '<root> <hdr>   <name>aj</name> </hdr> <dtls>   <dtl>     <price>1</price>   </dtl>   <dtl>     <price>7</price>   </dtl>   <dtl>     <price>3</price>   </dtl> </dtls> </root>'
SELECT CAST(@x AS XML).query('count(//dtl)')