SQLAlchemy: select over multiple tables
- by ahojnnes
Hi,
I wanted to optimize my database query:
link_list = select(
columns=[link_table.c.rating, link_table.c.url, link_table.c.donations_in],
whereclause=and_(
not_(link_table.c.id.in_(
select(
columns=[request_table.c.recipient],
whereclause=request_table.c.donator==donator.id
).as_scalar()
)),
link_table.c.id!=donator.id,
),
limit=20,
).execute().fetchall()
and tried to merge those two selects in one query:
link_list = select(
columns=[link_table.c.rating, link_table.c.url, link_table.c.donations_in],
whereclause=and_(
link_table.c.active==True,
link_table.c.id!=donator.id,
request_table.c.donator==donator.id,
link_table.c.id!=request_table.c.recipient,
),
limit=20,
order_by=[link_table.c.rating.desc()]
).execute().fetchall()
the database-schema looks like:
link_table = Table('links', metadata,
Column('id', Integer, primary_key=True, autoincrement=True),
Column('url', Unicode(250), index=True, unique=True),
Column('registration_date', DateTime),
Column('donations_in', Integer),
Column('active', Boolean),
)
request_table = Table('requests', metadata,
Column('id', Integer, primary_key=True, autoincrement=True),
Column('recipient', Integer, ForeignKey('links.id')),
Column('donator', Integer, ForeignKey('links.id')),
Column('date', DateTime),
)
There are several links (donator) in request_table pointing to one link in the link_table. I want to have links from link_table, which are not yet "requested".
But this does not work. Is it actually possible, what I'm trying to do? If so, how would you do that?
Thank you very much in advance!
