User-defined functions are extensions to PowerCenter transformation language. It allows you to create complex expressions using the built-in functions and operators and reuse them in PowerCenter mappings. User-defined functions are two types.
Public : Callable from any user-defined function, transformation expression, link condition expression, or task expression.
Private : Callable from another user-defined function. Create a private function when you want the function to be part of a more complex function. The simple function may not be usable independently of the complex function.
Creating User Defined Functions
You can create a user defined function from Informatica PowerCenter Designer tool. You can invoke the User-Defined Function dialog box from main menu Tools > User-Defined Functions > New. If u want a user defined function to convert the phone number into (XXX) XXX-XXXX format.
We can define the function here to convert PHONE_NUMBER into required string formatted in (XXX) XXX-XXXX. The expression editor shows the logic used within the user defined function. User defined functions can be used in any expressions just like any other functions. You can choose the available user defined functions from the functions explorer.