Group by hour in SQLAlchemy?

Question

How do I group query results by the hour part of a datetime column in SQLAlchemy?

Answer 1

In Oracle, use func.trunc(MyTable.dt, 'HH')

It is a bit finicky, however. This fails:

q = session.query(func.trunc(MyTable.dt, 'HH'), func.sum(MyTable.qty) \
           .group_by(func.trunc(MyTable.dt, 'HH'))

But this succeeds:

trunc_date = func.trunc(MyTable.dt, 'HH')
q = session.query(trunc_date, func.sum(MyTable.qty) \
           .group_by(trunc_date)

Thanks to this thread for the tip.