I tried using "Exist" and "IN". Not only did I not succeed, it didn't seem as an efficient solution.
Here is a simplified example:

TblMyTable
WorkerUserName  -  WorkerDegree  -  ManagerUserName  -  ManagerDegree

I need a query where there is a mutual connection / existence.
What I mean is only where the worker, ex. "John" has a manager named "Mary", and where Mary the manager has a worker named "John".

John the worker can have several managers and Mary the manager can have several workers.
So the result will be (the order doesn't matter) ideally in one line:
John - BSc  --  Mary - M.A.
or
Mary - M.A.  --  John - BSc

The punchline is it's only one table. it is not really managers and workers, this is just a simplification of the situation.
In the real situation both are equal, in a Table of names of users working with other users. Database is SQL 2005.

Many thanx in advance