python - get diff between 2 columns in postgresql by sqlalchemy -


i have posgresql , 2 columns datetime values. how can difference between columns sqlalchemy? ideally, need 1 row max difference value

assuming have defined classes , other code required create session database, can query maximum difference this:

# code set database engine...  class sometable(base):     __tablename__ = 'some_table'     id_ = column(integer, primary_key=true)     datetime_1 = column(datetime)     datetime_2 = column(datetime)  # code set session...  >>> sqlalchemy.sql import func >>> q = session.query(func.max(sometable.datetime_1 - sometable.datetime_2)) >>> print(q) select max(some_table.datetime_1 - some_table.datetime_2) max_1  some_table >>> print(q.one()) (datetime.timedelta(133, 28552, 844875),) >>> diff = q.scalar()    # value directly >>> diff datetime.timedelta(133, 28552, 844875) >>> print(diff) 133 days, 7:55:52.844875

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