parse xml as table - sql

Question

I have some xml like:
<MyDetails>
<detail key="key1" value="value1" />
<detail key="key2" value="value2" />
<detail key="key3" value="value3" />
<detail key="key4" value="value4" />
</MyDetails>
And I want to be able to parse it in a table format of two columns Key, and Value. How can I create a SQL function to achieve this by specifying a Node path i.e. in this case '/MyDetails/detail' and KeyAttributeName and ValueAttributeName. I created the following function but it gives me the error:
ALTER FUNCTION [dbo].[GetXmlTable] (
#XmlSource XML,
#HierarchyPath NVARCHAR(50) = '',
#SpecificKey NVARCHAR(255) = NULL,
#KeyAttributeName NVARCHAR(50) = 'key',
#ValueAttributeName NVARCHAR(50) = 'value'
)
RETURNS #Table TABLE (
[Key] NVARCHAR(255),
[Value] NVARCHAR(500)
)
AS
BEGIN
DECLARE #KeyAttribute NVARCHAR (50) = '#' + #KeyAttributeName
DECLARE #ValueAttribute NVARCHAR (50) = '#' + #ValueAttributeName
DECLARE #Path NVARCHAR (50) = '/' + #HierarchyPath
INSERT INTO #Table
SELECT XmlElement.Attribute.value(#KeyAttribute, 'nvarchar(255)') AS [Key]
,XmlElement.Attribute.value(#ValueAttribute, 'nvarchar(500)') AS [Value]
FROM #XmlSource.nodes(#Path) AS XmlElement(Attribute)
WHERE #SpecificKey IS NULL OR XmlElement.Attribute.value(#KeyAttribute, 'nvarchar(255)') = #SpecificKey
RETURN
END
GO
Error:
Msg 8172, Level 16, State 1, Procedure GetXmlTable, Line 12 The
argument 1 of the XML data type method "nodes" must be a string
literal.
Looking to call the function like this:
select * from dbo.GetXmlTable(CAST('<MyDetails>
<detail key="key1" value="value1" />
<detail key="key2" value="value2" />
<detail key="key3" value="value3" />
<detail key="key4" value="value4" />
</MyDetails>' as XML), 'MyDetails/detail', default, default, default)
UPDATE---------------
I tried using sql variable syntax but the table returned is blank. Can you please point out what I might be doing wrong:
DECLARE #KeyAttr VARCHAR(50) = N'#' + #KeyAttributeName
DECLARE #ValueAttr VARCHAR(50) = N'#' + #ValueAttributeName
DECLARE #Path VARCHAR(100) = '/' + #HierarchyPath
INSERT INTO #Table
SELECT XmlElement.Attribute.value('(*[local-name() = sql:variable("#KeyAttr")])[1]', 'nvarchar(255)') AS [Key]
,XmlElement.Attribute.value('(*[local-name() = sql:variable("#ValueAttr")][1])', 'nvarchar(500)') AS [Value]
FROM #XmlSource.nodes('(*[local-name() = sql:variable("#Path")])') AS XmlElement(Attribute)
WHERE #SpecificKey IS NULL OR XmlElement.Attribute.value('(*[local-name() = sql:variable("#KeyAttr")])[1]', 'nvarchar(255)') = #SpecificKey

Answer 1

This query will shred your XML into a simple table;
declare #xml xml = '<MyDetails>
<detail key="key1" value="value1" />
<detail key="key2" value="value2" />
<detail key="key3" value="value3" />
<detail key="key4" value="value4" />
</MyDetails>'
select
t.c.value('#key', 'varchar(100)') as [key],
t.c.value('#value', 'varchar(100)') as value
from
#xml.nodes('/MyDetails/detail') as t(c)
The error "The argument 1 of the XML data type method "nodes" must be a string literal." means exactly what it says - you can't pass a variable as the argument to the nodes() method. You can however reference variables in the XQuery passed to Nodes() - see sql:variable() for more info.