How to select distinct value

Question

I need to select all supervisor records. Our HR employee table set up like below

Firstname	Lastname	Email	Supervisor
Frank	Johns	fjohns	Taylor, Don
Pat	Hope	phope	Taylor, Don
Jen	Dow	jdow	Taylor, Don
Taylor	Don	tdon	Olson, Mike
Kim	Ronda	kronda	Olson, Mike
Rob	Smith	rsmith	Olson, Mike
Mike	Olson	molson	null

The final result should be like this

Firstname	Lastname	Email	Supervisor
Taylor	Don	tdon	Olson, Mike
Mike	Olson	molson	null

If I use Distinct on supervisor then it gives me a list of supervisor but not their info. Please help

Answer 1

This should work (I assume the transposed First / Last for Don Taylor is a typo).

SELECT DISTINCT d.Firstname, d.Lastname, d.Email, d.Supervisor
FROM MyTable d
INNER JOIN MyTable sup ON sup.Supervisor = d.Lastname + ', ' + d.Firstname;

or

SELECT Firstname, Lastname, Email, Supervisor
FROM MyTable
WHERE Lastname + ', ' + Firstname IN (
    SELECT Supervisor
    FROM MyTable
    WHERE Supervisor IS NOT NULL
);