How to query SQL Server XML column - sql-server

Question

I have a table which contains a XML column and I need to get a value from the XML.
<ArrayOfItem>
<Item>
<Key>Member_Claim_Id</Key>
<Value>1802538</Value>
</Item>
<Item>
<Key>Reverify</Key>
<Value>0</Value>
</Item>
<Item>
<Key>RequestNumber</Key>
<Value>First Request</Value>
</Item>
</ArrayOfItem>
Sometimes Reverify key will be present in the XML document, and other times it won't. The document can contain other key / value pairs as well.
But RequestNumber key / value pair will always be present, but it might be the second or third key / value item in the document. So I could have:
<ArrayOfItem>
<Item>
<Key>Member_Claim_Id</Key>
<Value>1802538</Value>
</Item>
<Item>
<Key>RequestNumber</Key>
<Value>First Request</Value>
</Item>
</ArrayOfItem>
Currently I am using this:
SELECT TOP 10 *
FROM dbo.myTable
WHERE Parameters.value('(/ArrayOfItem/Item/Value)[2]', 'varchar(max)') LIKE '%revision%'
ORDER BY Id DESC
But I was assuming that RequestNumber was always the 2nd Key/Value Item in the document, but I just learned that that is not always the case.
Let's say the table looks like:
CREATE TABLE dbo.myTable
(
Parameters XML NOT NULL,
Field1 VARCHAR(50) NULL
)
INSERT INTO dbo.myTable (Parameters, Field1)
VALUES
( '<ArrayOfItem>
<Item>
<Key>Member_Claim_Id</Key>
<Value>1802538</Value>
</Item>
<Item>
<Key>Reverify</Key>
<Value>0</Value>
</Item>
<Item>
<Key>RequestNumber</Key>
<Value>First Request</Value>
</Item>
</ArrayOfItem>', -- XMLParameters - xml
'myText' -- Field1 - varchar(50)
)
and I want the value of /ArrayOfItem/Item/Value where the key is RequestNumber.
Thank you for your help.

Answer 1

Please try the following solution.
SQL
-- DDL and sample data population, start
DECLARE #tbl TABLE (ID INT IDENTITY PRIMARY KEY, Parameters XML NOT NULL);
INSERT INTO #tbl (Parameters) VALUES
(N'<ArrayOfItem>
<Item>
<Key>Member_Claim_Id</Key>
<Value>1802538</Value>
</Item>
<Item>
<Key>Reverify</Key>
<Value>0</Value>
</Item>
<Item>
<Key>RequestNumber</Key>
<Value>First Request</Value>
</Item>
</ArrayOfItem>');
-- DDL and sample data population, end
DECLARE #param VARCHAR(30) = 'RequestNumber';
SELECT ID
, c.value('(Key/text())[1]', 'VARCHAR(30)') AS [Key]
, c.value('(Value/text())[1]', 'VARCHAR(30)') AS [Value]
FROM #tbl
CROSS APPLY Parameters.nodes('/ArrayOfItem/Item[Key[text()=sql:variable("#param")]]') AS t(c);
Output
+----+---------------+---------------+
| ID | Key | Value |
+----+---------------+---------------+
| 1 | RequestNumber | First Request |
+----+---------------+---------------+