How to insert xml into a node in another xml using XQuery? - sql

Question

I have two xml variable say #res, #student in a stored proc in SQL server 2005.
#res contains
<Subject>English</Subject>
<Marks>67</Marks>
<Subject>Science</Subject>
<Marks>75</Marks>
#student contains:
<Student>
<Name>XYZ</Name>
<Roll>15</Roll>
<Result />
<Attendance>50</Attendance>
</Student>
I need to insert the xml of #res into the node Result in #student variable using XQuery.
How to implement that?
Please help.

Answer 1

In SQL Server 2008, it's pretty easy:
DECLARE #res XML = '<Subject>English</Subject>
<Marks>67</Marks>
<Subject>Science</Subject>
<Marks>75</Marks>'
DECLARE #student XML = '<Student>
<Name>XYZ</Name>
<Roll>15</Roll>
<Result />
<Attendance>50</Attendance>
</Student>'
SET #student.modify('insert sql:variable("#res") as first into (/Student/Result)[1]')
SELECT #student
That gives me the output:
<Student>
<Name>XYZ</Name>
<Roll>15</Roll>
<Result>
<Subject>English</Subject>
<Marks>67</Marks>
<Subject>Science</Subject>
<Marks>75</Marks>
</Result>
<Attendance>50</Attendance>
</Student>
Unfortunately, the ability to call .modify() and use a sql:variable in the insert statement was introduced with SQL Server 2008 only - doesn't work in SQL Server 2005.
I don't see how you could do this in SQL Server 2005, other than resorting back to ugly string parsing and replacement:
SET #student =
CAST(REPLACE(CAST(#student AS VARCHAR(MAX)),
'<Result/>',
'<Result>' + CAST(#res AS VARCHAR(MAX)) + '</Result>') AS XML)
Marc

Answer 2

This will work in SQL 2005 and is mostly an xquery solution:
DECLARE #res xml
SET #res =
'<Subject>English</Subject>
<Marks>67</Marks>
<Subject>Science</Subject>
<Marks>75</Marks>'
DECLARE #student xml
SET #student =
'<Student>
<Name>XYZ</Name>
<Roll>15</Roll>
<Result />
<Attendance>50</Attendance>
</Student>'
DECLARE #final XML
SET #final = CAST(CAST(#student AS VARCHAR(MAX)) + '<test>' + CAST(#res AS VARCHAR(MAX)) + '</test>' AS XML)
SET #final.modify('insert /test/* into (/Student/Result)[1]')
SET #final.modify('delete /test')
SELECT #final
You can set your #student variable to #final at that point if you need to do that. The name of "test" for the node was just what I chose to use. You can use any name as long as it will not already appear in your XML.
You basically just throw the two XML strings together so that they are both available to xquery at once.

Answer 3

You may also try to go back to relational data and than back to xml; something like:
DECLARE #res xml =
'<result>
<StudentID>1</StudentID>
<Subject>English</Subject>
<Marks>67</Marks>
</result>
<result>
<StudentID>1</StudentID>
<Subject>Science</Subject>
<Marks>75</Marks>
</result>'
DECLARE #student xml =
'<Student>
<StudentID>1</StudentID>
<Name>XYZ</Name>
<Roll>15</Roll>
<Attendance>50</Attendance>
</Student>'
;
WITH cte_1
AS ( SELECT t.c.value('StudentID[1]', 'int') AS [StudentID]
,t.c.value('Subject[1]', 'varchar(50)') AS [Subject]
,t.c.value('Marks[1]', 'int') AS [Marks]
FROM #res.nodes('/result') AS t ( c )
),
cte_2
AS ( SELECT t.c.value('StudentID[1]', 'int') AS [StudentID]
,t.c.value('Name[1]', 'varchar(50)') AS [Name]
,t.c.value('Roll[1]', 'int') AS [Roll]
,t.c.value('Attendance[1]', 'int') AS [Attendance]
FROM #student.nodes('/Student') AS t ( c )
)
SELECT student.StudentID
,student.[Name]
,student.Roll
,student.Attendance
,( SELECT result.[Subject]
,result.Marks
FROM cte_1 AS result
WHERE student.StudentID = result.StudentID
FOR
XML AUTO
,TYPE
,ELEMENTS
)
FROM cte_2 AS student
FOR XML AUTO
,ELEMENTS
Returns:
<student>
<StudentID>1</StudentID>
<Name>XYZ</Name>
<Roll>15</Roll>
<Attendance>50</Attendance>
<result>
<Subject>English</Subject>
<Marks>67</Marks>
</result>
<result>
<Subject>Science</Subject>
<Marks>75</Marks>
</result>
</student>
Not exactly your example, but close.