SET @row_number := 0;

-- Query to rank each race, smaller row number means better result
SELECT UserId, @row_number:=CASE

--Better time
        WHEN @raceId = RaceId AND @lastTime < RaceTime

            THEN @row_number + 1

--Tie
WHEN @raceId = RaceId

THEN @row_number = @row_number

--Start new race
        ELSE 1

    END AS Ranking,

    @raceId:=RaceId RaceId,
@lastTime:= RaceTime RaceTime

FROM Races
ORDER BY RaceId ASC, RaceTime ASC