Python-сообщество

#таблица месторождений
field_table = Table('oil_field', metadata,
    Column('rn', Integer, primary_key=True),
    Column('name', String(50))
)

class Field(object):
    def __init__(self, name):
        self.name = name
    def __repr__(self):
       return "<Field ('%d', %s')>" % (self.rn, self.name.encode('utf-8'))

well_table = Table('well', metadata,
    Column('rn', Integer, primary_key=True),
    Column('prn', Integer, ForeignKey('oil_field.rn')),
    Column('well_id', String(20)),
    Column('name', String(20)),
    Column('latitude', Numeric(15, 6)),
    Column('td', Numeric(15, 6)),
    Column('datun_elevation', Numeric(15, 6)),
    Column('rus_name', String(20))
)

#таблица скважин
class Well(object):
    def __init__(self, well_id, name, latitude=0, td = 0, datum=0, rus_name=''):
        self.well_id = well_id
        self.name = name
        self.latitude = latitude
        self.td = td
        self.datun_elevation = datum
        self.rus_name = rus_name
    def __repr__(self):
        return "<Well: (%d, %s, %s)>" % (self.rn, self.name.encode('utf-8'), self.well_id.encode('utf-8'))

#таблица источников данных
source_table = Table('src', metadata,
    Column('rn', Integer, primary_key=True), #чисто, чтобы было
    Column('oil_field', Integer, ForeignKey('oil_field.rn')),
    Column('src', Integer),
    Column('name', String(100))
)

class Source(object):
    def __init__(self, oil_field, src, name):
        self.oil_field = oil_field
        self.src = src
        self.name = name

    def __repr__(self):
        return '<Source: (%s, %s)>' % (self.src, self.name.encode('utf-8'))

#мапим всё
mapper(Well, well_table)
mapper(Source, source_table)

mapper(Field, field_table, properties={
    'wells':    relation(Well,   backref='wells'),
    'sourcess': relation(Source, backref='sourcess'),
    }
)

        f = db.Session().query(db.Field).filter_by(rn=33).first()
        print f.wells
        print f.sourcess

(33,)
('33',)
(33,)
(Decimal("33"),)