Get the names of attributes from an element in a SQL XML column

问题

For this xml (in a SQL 2005 XML column):

<doc>
 <a>1</a>
 <b ba="1" bb="2" bc="3" />
 <c bd="3"/>
<doc>

I'd like to be able to retrieve the names of the attributes (ba, bb, bc, bd) rather than the values inside SQL Server 2005. Well, XPath certainly allows this with name() but SQL doesn't support that. This is my chief complaint with using XML in SQL; you have to figure out which parts of the XML/Xpath/XQuery spec are in there.

The only way I can think of to do this is to build a CLR proc that loads the XML into an XML Document (iirc) and runs the XPath to extract the names of the nodes. I'm open to suggestions here.

回答1:

DECLARE @xml as xml
DECLARE @path as varchar(max)
DECLARE @index int, @count int

SET @xml = 
'<doc>
 <a>1</a>
 <b ba="1" bb="2" bc="3" />
 <c bd="3"/>
</doc>'



SELECT @index = 1

SET @count = @xml.query('count(/doc/b/@*)').value('.','int')

WHILE @index <= @count 
BEGIN
    SELECT  @xml.value('local-name((/doc/b/@*[sql:variable("@index")])[1])', 'varchar(max)')
    SET @index = @index + 1
END

for element 'b'

it returns

You can build a loop to get attributes for each element in the xml.

BTW The XML in your sample should be closed at closing doc tag.

回答2:

DECLARE @xml as xml

SET @xml = 
'<doc>
 <a>1</a>
 <b ba="1" bb="2" bc="3" />
 <c bd="3"/>
</doc>'

SELECT DISTINCT
 CAST(Attribute.Name.query('local-name(.)') AS VARCHAR(100)) Attribute,
 Attribute.Name.value('.','VARCHAR(100)') Value
FROM @xml.nodes('//@*') Attribute(Name)

Returns:

Attribute Value

ba 1

bb 2

bc 3

bd 3

回答3:

this:

declare @xml as xml

set @xml = 
'<doc>
 <a>1</a>
 <b ba="1" bb="2" bc="3" />
 <c bd="3"/>
</doc>'

select @xml.query('
    for $attr in /doc/b/@*
    return local-name($attr)')

returns:

ba bb bc

回答4:

Declare @xml Xml = '<doc><a>1</a><b ba="1" bb="2" bc="3" /><c bd="3"/></doc>'

Select n.value('local-name(.)', 'varchar(max)')  from @xml.nodes('/doc/*/@*') a(n)

Returns ba bb bc bd

来源：https://stackoverflow.com/questions/241407/get-the-names-of-attributes-from-an-element-in-a-sql-xml-column

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.net

sql-server

xml

xpath

sqlclr