User-defined functions#
Like functions in programming languages, user-defined functions (UDF) are routines that accept parameters, perform an action, and return the result of that action.
A table valued user-defined function (TVUDF) takes zero or more input parameters and returns a tabular result set.
When a parameter of the function has a default value, the keyword DEFAULT must be specified when calling the function to get the default value. User-defined functions don’t support output parameters.
The only type of UDF currently supported is CLR table-valued function, used to encapsulate a REST call.