class Material(models.Model):
    name = models.CharField(max_length=100)
    nomer_materiala = models.CharField(max_length=50)
    count = models.DecimalField(max_digits=10, decimal_places=5)
    MVZ = models.CharField(max_length=50)
    comment = models.TextField ()
    obect = models.CharField(max_length=30)

    def __unicode__(self):
        return '%s %s' % (self.nomer_materiala, self.name)

class Rashod(models.Model):
    material = models.ForeignKey(Material)
    count = models.DecimalField(max_digits=10, decimal_places=5)
    proekt = models.CharField(max_length=30)
    ispolnitel =  models.ForeignKey(Person)
    #building = models.CharField(max_length=30)

SELECT ostatki_Material.Name, Sum(ostatki_Rashod.Count)
FROM ostatki_Rashod INNER JOIN ostatki_Material ON ostatki_Rashod.Material_id = ostatki_Material.ID
GROUP BY ostatki_Material.Name;

select sum(count) from ostatki_rashod where ostatki_rashod.nomer_materiala = nomer_materiala

Rashod.objects.all().count()