Microsoft® Visual Studio® 2010 Unleashed

Creating User-Defined Functions

User-defined functions are bodies of code/SQL designed to be reusable across a variety of possible consumers: stored procedures, applications, or even other functions. In that respect, they are no different from functions written in C# or Visual Basic. They are routines that can accept parameters and return a value. User-defined functions return scalar values (for example, a single value) or a resultset containing rows and columns of data.

One example of a user-defined function might be one that accepts a date and then determines whether the day is a weekday or weekend. Stored procedures or other functions in the database can then use the function as part of their processing.

Because user-defined functions are ...