CLR User-Defined Functions
Applies to: 
SQL Server
User-defined functions are routines that can take parameters, perform calculations or other actions, and return a result. Beginning with SQL Server 2005 (9.x), you can write user-defined functions in any Microsoft .NET Framework programming language, such as Microsoft Visual Basic .NET or Microsoft Visual C#.
There are two types of functions: scalar, which returns a single value, and table-valued, which returns a set of rows.
The following table lists the topics in this section.
CLR Scalar-Valued Functions
Covers implementation requirements and examples of scalar-valued functions.
CLR Table-Valued Functions
Discusses how to implement and use table-valued functions (TVFs), as well as differences between Transact-SQL and common language runtime (CLR) TVFs.
CLR User-Defined Aggregates
Describes how to implement and use user-defined aggregates.