SQL Script to Break up XML into Columns - sql

Question

I have a table that stores audit history in an XML format. Each document has its own history. How can I parse out he XML data per document whereby each column in the XML represents and an actual column and action that took place in that column.
Example:
<auditElement><field id="2881159" type="5" name="Responsiveness" formatstring=""><unSetChoice>2881167</unSetChoice><setChoice>2881166</setChoice></field></auditElement>
UnsetChoice and Set Choice are the columns.
Name=represents the action.

Answer 1

Xml can be parsed using features such as XQuery, or OpenXml.
Here's an example of xquery:
declare #xml as xml = '<auditElement><field id="2881159" type="5" name="Responsiveness"' +
' formatstring=""><unSetChoice>2881167</unSetChoice>' +
'<setChoice>2881166</setChoice></field></auditElement>';
SELECT
Nodes.node.value('(field/#id)[1]', 'INT') AS FieldId,
Nodes.node.value('(field/#name)[1]', 'varchar(50)') AS FieldName,
Nodes.node.value('(field/unSetChoice/text())[1]', 'INT') AS OldValue,
Nodes.node.value('(field/setChoice/text())[1]', 'INT') AS NewValue
FROM
#xml.nodes('//auditElement') AS Nodes(node);
Result:
FieldId FieldName OldValue NewValue
----------- -------------------------------------------------- ----------- -----------
2881159 Responsiveness 2881167 2881166

Answer 2

You can use OUTER APPLY and then break down the parts of the XML field.
The value() method takes XQuery expressions.
For example:
DECLARE #T TABLE (Id int identity(1,1) primary key, XmlCol1 xml);
insert into #T (XmlCol1) values
('<auditElement><field id="2881159" type="5" name="Responsiveness" formatstring=""><unSetChoice>2881167</unSetChoice><setChoice>2881166</setChoice></field></auditElement>'),
('<auditElement><field id="2881160" type="6" name="Responsiveness" ><unSetChoice>2881187</unSetChoice><setChoice>2881188</setChoice></field></auditElement>');
select *
from (
select
Id,
a.field.value('#id', 'int') as xmlid,
a.field.value('(unSetChoice)[1]', 'int') as unSetChoice,
a.field.value('(setChoice)[1]', 'int') as setChoice,
a.field.value('#type', 'int') as type,
a.field.value('#name', 'varchar(max)') as name,
a.field.value('#formatstring', 'varchar(max)') as formatstring
from #T t
outer apply t.XmlCol1.nodes('/auditElement/field') as a(field)
where a.field.value('#id', 'int') > 0 and Id > 0
) q
where name = 'Responsiveness';
Result:
Id xmlid unSetChoice setChoice type name formatstring
1 2881159 2881167 2881166 5 Responsiveness
2 2881160 2881187 2881188 6 Responsiveness NULL