Parse XML into a (XPath, Value) pair - sql-server

Question

Working with XML in SQL Server, given this XML:
<A>
<B>123</B>
<C>
<Cs>234</Cs>
<Cs>345</Cs>
<Cs>12</Cs>
<Cs>2346</Cs>
</Cs>
</A>
I'd like to produce a result set that looks like this:
xpath
value
(/A/B)[1]
123
(/A/C/Cs)[1]
234
(/A/C/Cs)[2]
345
(/A/C/Cs)[3]
12
(/A/C/Cs)[4]
2346
Is there a trick that can do this without walking through the XML? Added bonus would include the ability to start somewhere other than the document root. You could pass /A/C to this routine and it would only give the paths under that element.

Answer 1

This is one of the rare cases when the archaic OPENXML() is handy.
XQuery 3.0 introduced a real solution for such task: fn:path() function long time ago in 2014. Unfortunately, MS SQL Server supports just a subset of XQuery 1.0
Back to mundane earth.
SQL
DECLARE #xml XML =
N'<A>
<B>123</B>
<C>
<Cs>234</Cs>
<Cs>345</Cs>
<Cs>12</Cs>
<Cs>2346</Cs>
</C>
</A>';
DECLARE #DocHandle INT;
EXEC sp_xml_preparedocument #DocHandle OUTPUT, #xml;
;WITH rs AS
(
SELECT * FROM OPENXML(#DocHandle,'/*')
), cte AS
(
-- anchor
SELECT id
,ParentID
--, nodetype
, [text]
,CAST(id AS VARCHAR(100)) AS [Path]
,CAST('/' + rs.localname AS VARCHAR(1000))
+ N'['
+ CAST(ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS NVARCHAR)
+ N']' AS [XPath]
FROM rs
WHERE ParentID IS NULL
UNION ALL
--recursive member
SELECT t.id
,t.ParentID
--, nodetype = (SELECT nodetype FROM rs WHERE id = t.ParentID)
, t.[text]
, CAST(a.[Path] + ',' + CAST( t.ID AS VARCHAR(100)) AS VARCHAR(100)) AS [Path]
, CAST(a.[XPath] + '/' + IIF(t.nodetype = 2, '#', '')
+ t.localname AS VARCHAR(1000))
+ N'['
+ TRY_CAST(ROW_NUMBER() OVER(PARTITION BY t.localname ORDER BY (SELECT 1)) AS NVARCHAR)
+ N']' AS [XPath]
FROM rs AS t
INNER JOIN cte AS a ON t.ParentId = a.id
)
SELECT ID, ParentID, /*nodetype,*/ [Path]
, REPLACE([XPath],'#text','text()') AS XPath
, [text] AS [Value]
FROM cte
WHERE [text] IS NOT NULL
--AND CAST([text] AS VARCHAR(30)) = '12345'
ORDER BY [Path];
EXEC sp_xml_removedocument #DocHandle;
Output
+----+----------+----------+----------------------------+-------+
| ID | ParentID | Path | XPath | Value |
+----+----------+----------+----------------------------+-------+
| 8 | 2 | 0,2,8 | /A[1]/B[1]/text()[1] | 123 |
| 9 | 4 | 0,3,4,9 | /A[1]/C[1]/Cs[1]/text()[1] | 234 |
| 10 | 5 | 0,3,5,10 | /A[1]/C[1]/Cs[2]/text()[1] | 345 |
| 11 | 6 | 0,3,6,11 | /A[1]/C[1]/Cs[3]/text()[1] | 12 |
| 12 | 7 | 0,3,7,12 | /A[1]/C[1]/Cs[4]/text()[1] | 2346 |
+----+----------+----------+----------------------------+-------+

Answer 2

You can use a recursive CTE. You pass in the XML document in #xml. If you need to use a table to get the XML, you can use CROSS APPLY YourXml.nodes instead of FROM #XML.nodes.
WITH cte AS (
SELECT
xpath = CONCAT(v.name, '[', ROW_NUMBER() OVER (PARTITION BY v.name ORDER BY (SELECT 1)), ']'),
value = x.nd.value('text()[1]','nvarchar(100)'),
child = x.nd.query('*')
FROM #xml.nodes('*') x(nd)
CROSS APPLY (VALUES (x.nd.value('local-name(.)[1]','nvarchar(max)'))) v(name)
UNION ALL
SELECT
xpath = CONCAT(cte.xpath, '/', v.name, '[', ROW_NUMBER() OVER (PARTITION BY xpath, v.name ORDER BY (SELECT 1)), ']'),
value = x.nd.value('text()[1]','nvarchar(100)'),
child = x.nd.query('*')
FROM cte
CROSS APPLY cte.child.nodes('*') x(nd)
CROSS APPLY (VALUES (x.nd.value('local-name(.)[1]','nvarchar(max)'))) v(name)
)
SELECT
xpath = CONCAT('/', xpath, '/text()[1]'),
value
FROM cte
WHERE value IS NOT NULL;
db<>fiddle
Unfortunately, you cannot use the ancestor:: axis, which would have made this much easier.
If SQL Server supported ancestor:: you could do something like this
SELECT
xpath = '(' + x.nd.query('for $n in ancestor::* return concat("/", local-name($n))') + '/text())[1]',
value = x.nd.value('text()[1]','nvarchar(100)')
FROM #xml.nodes('//*[text()]') x(nd)