La tua richiesta sembra soddisfacente, ma potresti migliorarla per chiarezza:
INSERT INTO monthlystats (id, server, time, uptime, players, rank)
VALUES (09126, 6, 0912, 302, 0, 1)
ON DUPLICATE KEY UPDATE
uptime = GREATEST(uptime, VALUES(uptime)),
players = GREATEST(players, VALUES(players)),
rank = GREATEST(rank, VALUES(rank))
