Question

I have a table from a vendor application that stores some xml data into a column of type varchar(200).

Table structure and sample data is here

declare @table table 
(
 MerchantID int not null
,Data       varchar(200) not null)   

insert into @table  
select 1, '<product><productID>1</productID><pdesc>ProductDesc</pdesc></product>'  
union all
select 2, '<product><itemid>1</itemid><itemname>name of item</itemname></product>'

Is there a way to transform raw xml data into relation format like below in a stored procedure?

for e.g when merchantID passed is 1

MerchantID   productID   pdesc
   1             1       Product Desc

when MerchantID pass is 2 output should be

MerchantID  itemid  itemname
   2          1     name of item

Answer 1

You can use XPath in SQL Server to access XML data nodes.

Here’s an example, using your data.

declare @test xml
set @test = '<product><productID>1</productID><pdesc>ProductDesc</pdesc></product>'

SELECT  
@test.value('(/product/productID/node())[1]', 'nvarchar(max)') as productID, 
@test.value('(/product/pdesc/node())[1]', 'nvarchar(max)') as pdesc

From there, you should be able to perform your union like so:

SELECT 1,
xmlfield1.value('(/product/productID/node())[1]', 'int') as id, 
xmlfield1.value('(/product/pdesc/node())[1]', 'nvarchar(max)') as desc

union

SELECT 2, 
xmlfield2.value('/product/itemid/node())[1]', 'int') as id, 
xmlfield2.value('/product/itemname/node())[1]', 'nvarchar(max)') as desc

if your data is in the same column, you can use a case statement to resolve it.

case 
  when merchantId = 1 data.value('(/product/productID/node())[1]', 'int') 
  else data.value('/product/itemid/node())[1]', 'int')
  end as id