Сам не пробовал, но очевидно ответ следует искать в Crystal Report`s Developers Help. Очевидно что-то из этой серии:

Special purpose functions
You can define several special purpose functions in your Class Module in addition to the User-Defined Functions that you are creating. The Crystal Reports Formula Editor can look for and process any of the following class methods:

Function UFInitialize: Integer;
Function UFTerminate: Integer;
Procedure UFStartJob (job: Integer)
Procedure UFEndJob (job: Integer)

Be sure to declare the methods in your code exactly as they appear above. If not declared correctly, they will be ignored by Crystal Reports. These methods are completely optional when creating your Delphi Automation Server. They are provided to assist you with the design of your User-Defined Functions.

UFStartJob
This procedure is called by Crystal Reports just before User-Defined Functions are evaluated (or reevaluated). The Crystal Reports job number is passed to the function as the only parameter. Use this function to handle any initialization on a per-job basis.

Кстати, имя пользователя может передать Oracle.