SQL Server: How do I use modify() to alter XML data in a column with a TEXT data type

Question

I'm trying to modify some XML values in a database. I can get it to work on columns that contain XML that are using the XML data type. However, I can't get it to work on TEXT columns.

Also, I can SELECT XML data on TEXT columns (by using CAST() to convert it to XML), but still can't UPDATE.

Example:

UPDATE [xmltest]  
SET [xmltext].modify('replace value of (/data/item[1]/text())[1] with "newvalue"')

Error: Cannot call methods on text.

Is there some way I can get this to work on a TEXT column? There's already TONS of data stored, so I'd rather not have to request to change the data type on the column.

Thanks!

Sunsu

Answer 1

You cannot directly modify this - what you can do is a three steps process:

• select the TEXT column from the table into a local XML variable
• modify the XML variable
• write back your changes to the database

Something like this:

-- declare new local variable, load TEXT into that local var
DECLARE @temp XML

SELECT 
     @temp = CAST(YourColumn AS XML) 
FROM 
     dbo.YourTable
WHERE
     ID = 5     -- or whatever criteria you have

-- make your modification on that local XML var
SET 
   @temp.modify('replace value of (/data/item[1]/text())[1] with "newvalue"') 

-- write it back into the table as TEXT column      
UPDATE 
   dbo.YourTable
SET 
   YourColumn = CAST(CAST(@temp AS VARCHAR(MAX)) AS TEXT)
WHERE
     ID = 5     -- or whatever criteria you have

It's a bit involved, but it works! :-)