Replace invalid XML characters using SQL query

Question

Hi,
   I am populating a dataset in .net with output from sql 2005 database. One of the columns in the table is a 'varchar(max)' type. This dataset is then converted to XML using WriteXml and written to a .xml document. But due to the presence of invalid characters, this process errors out.
Is there any way using which these invalid characters can be replaced at the database level itself when querying on the table?
The error that is produced is as follows:
'', hexadecimal value 0x1C, is an invalid character. Line 32201, position 924. 
Thanks,
Nisha

Answer 1

I see,
So we have a certain character that the XML processor does not like. What do you want to do with this character? Even if you manage to make an XML file wth this some how, you will get the same problem when another application tries to read it.
Probably you should replace those characters before converting the values to XML.
Another option is to put the values to the CDATA. This will be tough because the query might be little tricky. Here is an example that might help you.
Code Snippet
CREATE TABLE CDataTest (SomeValue NVARCHAR(50))
INSERT INTO CDataTest (SomeValue) SELECT 'Some Value ' + CHAR(25) + 'Some OtherValue'
SELECT * FROM CDataTest FOR XML AUTO, TYPE
error!!!
FOR XML could not serialize the data for node 'SomeValue' because it contains
a character (0x0019) which is not allowed in XML. To retrieve this data using
FOR XML, convert it to binary, varbinary or image data type and use the
BINARY BASE64 directive.
-- option using CDATA
SELECT
1
AS Tag,
NULL AS Parent,
(SELECT
SomeValue AS 'data()'
FROM CDataTest
FOR XML PATH('')) AS 'SomeValue!1!SomeValue!cdata'
FROM CDataTest
FOR XML EXPLICIT, TYPE
<SomeValue>
<SomeValue><![CDATA[Some Value &#x19;Some OtherValue]]></SomeValue>
</SomeValue>