SELECT track1.TrackId, track1.name, track1.bytes,
    (SELECT
        SUM(track2.bytes)/1000000
     FROM
        tracks track2
     WHERE
        track1.TrackId >= track2.TrackId
     ORDER BY
        track2.TrackId )
     AS SUMA_BAJTOW
FROM
    tracks track1
WHERE
    SUMA_BAJTOW <= 1024
ORDER BY
    track1.TrackId