spróbuj, używając CASE
Update MyTable
SET value = CASE
WHEN game_id = 1 AND x = -4 AND y = 8 THEN 1
WHEN game_id = 1 AND x = -3 AND y = 7 THEN 2
WHEN game_id = 2 AND x = 5 AND y = 2 THEN 3
ELSE value
END
WHERE game_ID IN (1,2,3) AND -- the purpose of this WHERE clause
x IN (-4, -3, 5) AND -- is to optimize the query by preventing from
y IN (8,7,2) -- performing full table scan.