How can I call a standard .NET assembly within SQL

Question

I am having an issue whereby a column within a table of mine has data which is encoded using the System.Xml.XmlConvert.Encode method.

Now I need to manipulate this data within SQL and have not found a way to duplicate the System.Xml.XmlConvert.Decode method.

So I've been investigating how I can use the System.XML namespace within SQL to access this method WITHOUT having to wrap it inside one of my own assemblies. Is this possible? i.e. how can I access this assembly directly via T-SQL?

Answer 1

There quite a few examples of writing add-ins using .NET for SQL. I believe you will need to have SQL 2005 or newer to create an add-in.

Here is an example that is particularly useful.

Creating CLR SQL User Defined Function to Validate Values Using Regular Expressions @ MSDN

In your case, you will probably want to write a function that takes a byte[] and returns a string (decode), along with a corresponding function that takes a string and returns a byte[].

Actually I'm not sure that you can directly use byte[], but you should be able to write a corresponding wrapper function in SQL that can take a hex string and turn it into a varbinary() if that is necessary.

edit:

Here are some more durable links to other references that are included in the prior link, just in case it ever disappears.

How to: Create and Run a CLR SQL User-Defined Function @ MSDN

Custom Attributes for CLR Routines @ TechNet