cursor = cnx.cursor()
cursor.execute("""
select
futar.id, futar.nev, sum(osszeg)

from futar
left join rendeles on rendeles.futar_id = futar.id

group by futar.id, futar.nev

order by 3 desc
""")

records = cursor.fetchall()

print('%3s) %-25s : %10s' % ('SSz', 'Név', 'Összeg'))

osszesen = 0
for row in records:
    if row[2] is not None:
        osszesen += float(row[2])

    print('%3d) %-25s : %10s' % row)

print('     %-25s : %10s' % ('Végösszeg', osszesen))