How to edit XML values using SQL queries? - sql

Question

I have an XML column UserDetails in a SQL Server database which has value like this:
<fleet>
<Setting name="city"/>
<UserSettings name="details">
<UserSettings name="A1">
<setting type="1" name="email"/>
<setting value="user"/>
</UserSettings>
<UserSettings name="A2">
<setting type="2" name="phone"/>
<setting value="technician"/>
</UserSettings>
</UserSettings>
</fleet>
I would to read from the db and add a new setting in
<UserSettings name="A2"> .
Can someone point me to what I should be doing?

Answer 1

You might use sql:variable() to introduce a value you've created externally. And you can use Xml.exist() to find XMLs which haven't got this new entry before:
DECLARE #myTbl TABLE(Descr VARCHAR(100),TheXml XML);
INSERT INTO #myTbl VALUES
(
'Setting "A3" doesn''t exist','<fleet>
<Setting name="city" />
<UserSettings name="details">
<UserSettings name="A1">
<setting type="1" name="email" />
<setting value="user" />
</UserSettings>
<UserSettings name="A2">
<setting type="2" name="phone" />
<setting value="technician" />
</UserSettings>
</UserSettings>
</fleet>'
)
,(
'Setting "A3" exists already','<fleet>
<Setting name="city" />
<UserSettings name="details">
<UserSettings name="A1">
<setting type="1" name="email" />
<setting value="user" />
</UserSettings>
<UserSettings name="A2">
<setting type="2" name="phone" />
<setting value="technician" />
</UserSettings>
<UserSettings name="A3">
<setting type="3" name="A3 setting" />
<setting value="this exists already" />
</UserSettings>
</UserSettings>
</fleet>'
);
DECLARE #NewSetting XML=
N'<UserSettings name="A3">
<setting type="3" name="new A3" />
<setting value="new data" />
</UserSettings>';
UPDATE #myTbl
SET TheXml.modify('
insert sql:variable("#NewSetting")
as last into (/fleet/UserSettings)[1]')
WHERE TheXml.exist(N'/fleet/UserSettings[#name="details"]/UserSettings[#name="A3"]')=0;
SELECT * FROM #myTbl

Answer 2

SQL SERVER provides methods to modify XML data, and a language to do it (XML DML).
You need to use the modify method with an insert xml dml statement.
Here is the complete example:
Sample data:
DECLARE #myDoc xml;
SET #myDoc =
'<fleet>
<Setting name="city" />
<UserSettings name="details">
<UserSettings name="A1">
<setting type="1" name="email" />
<setting value="user" />
</UserSettings>
<UserSettings name="A2">
<setting type="2" name="phone" />
<setting value="technician" />
</UserSettings>
</UserSettings>
</fleet>';
The statement:
SET #myDoc.modify('
insert <setting value="NEW SETTINGS" />
as first into (/fleet/UserSettings/UserSettings[#name="A2"])[1] ') ;
SELECT #myDoc;
Result:
<fleet>
<Setting name="city" />
<UserSettings name="details">
<UserSettings name="A1">
<setting type="1" name="email" />
<setting value="user" />
</UserSettings>
<UserSettings name="A2">
<setting value="NEW SETTINGS" />
<setting type="2" name="phone" />
<setting value="technician" />
</UserSettings>
</UserSettings>
</fleet>