Introduction to User-Defined Functions

User-defined functions are a class of procedures that return a single value to the calling environment. This section introduces creating, using, and dropping user-defined functions.

• Creating User-Defined Functions
  You use the CREATE FUNCTION statement to create user-defined functions. However, you must have RESOURCE authority.
• Calling User-Defined Functions
  A user-defined function can be used, subject to permissions, in any place you would use a built-in nonaggregate function.
• Dropping User-Defined Functions
  Once a user-defined function is created, it remains in the database until it is explicitly removed.
• Permissions to Execute User-Defined Functions
  A user-defined function is owned by the user who created it, and that user can execute it without permission.