Programming Microsoft® SQL Server™ 2008

CLR Functions

Let’s take everything we’ve discussed about SQL CLR stored procedures and deployment and apply it to SQL CLR functions. As any programmer knows, a function is a procedure that returns a value (or an object). Mainstream .NET functions typically return .NET types. SQL CLR functions, on the other hand, must return a SqlType. So to start with, we need to make sure that our classes that implement SQL CLR functions import the System.Data.SqlTypes namespace with a using statement. The SQL Server Project template for User-Defined Functions contains the appropriate using statement by default; you will need to add the statement manually to standard Class Library class code.

Once the namespace is imported, you can write the functions themselves. ...