Querying XML Node with a where criteria - sql-server

Question

I have a table with following attributes:
[Students]
ID Class Data (xml)
1 Secondary XML Data
Below is a sample xml structure that I store on the data attribute.
<Root>
<Data>
<Name>John</Name>
<Rank>1</Rank>
</Data>
<Data>
<Name>Peter</Name>
<Rank>2</Rank>
</Data>
</Root>
I want to write a sql query which will give me following data from the table:
ID, Class and Rank 2 student Name
My Query is
Select ID,Class,Data.value('(/Root/Data/Name)[1]', 'NVARCHAR(3)') AS [Rank 2 Student Name]
FROM [Students]
This works fine, but hardcoding the the node number to 1 is not a good idea here becuase if I add a new Data node in my xml then the data will change. And this is a possibility. So is there a way I can specify that return Name for the node where Rank value is 2.
Thanks.

Answer 1

you can use this:
DECLARE #tbl TABLE (xmlcol xml )
INSERT INTO #tbl
VALUES ('<Root>
<Data>
<Name>John</Name>
<Rank>1</Rank>
</Data>
<Data>
<Name>Peter</Name>
<Rank>2</Rank>
</Data>
</Root>')
SELECT *
FROM
(
SELECT r.d.value ('(./Name/text())[1]', 'varchar(50)') [Name],
r.d.value ('(./Rank/text())[1]', 'varchar(50)') [Rank]
FROM #tbl
CROSS APPLY xmlcol.nodes ('/Root/Data') R(d)
) P
WHERE P.[Rank] = 2
which will output the following result:
Name Rank
Peter 2

Answer 2

You can apply filter in xml as follows:
DECLARE #Students TABLE(ID int, Class varchar(10), Data xml)
INSERT #Students VALUES (1,'A', '<Root>
<Data>
<Name>John</Name>
<Rank>1</Rank>
</Data>
<Data>
<Name>Peter</Name>
<Rank>2</Rank>
</Data>
</Root>')
SELECT ID,Class,Data.value('(/Root/Data[Rank=2]/Name)[1]', 'NVARCHAR(5)') AS [Rank 2 Student Name]
FROM #Students
Result
ID Class Rank 2 Student Name
----------- ---------- -------------------
1 A Peter
Edit. If Rank contains free text, use quotes:
DECLARE #Students TABLE(ID int, Class varchar(10), Data xml)
INSERT #Students VALUES (1,'A', '<Root>
<Data>
<Name>John</Name>
<Rank>1</Rank>
</Data>
<Data>
<Name>Peter</Name>
<Rank>0:Company name</Rank>
</Data>
</Root>')
SELECT ID,Class,Data.value('(/Root/Data[Rank="0:Company name"]/Name)[1]', 'NVARCHAR(5)') AS [Rank 2 Student Name]
FROM #Students