SELECT p1.PLAYERID,
       f1.PLAYERNAME,
       p2.PLAYERID,
       f2.PLAYERNAME
FROM   PLAYER f1,
       PLAYER f2,
       PLAYS p1
       FULL OUTER JOIN PLAYS p2
                    ON p1.PLAYERID < p2.PLAYERID
                       AND p1.TEAMID = p2.TEAMID
GROUP  BY p1.PLAYERID,
          f1.PLAYERID,
          p2.PLAYERID,
          f2.PLAYERID
HAVING Count(p1.PLAYERID) = Count(*)
       AND Count(p2.PLAYERID) = Count(*)
       AND p1.PLAYERID = f1.PLAYERID
       AND p2.PLAYERID = f2.PLAYERID;