Check out example codes for "less than date query sqlachemy". It will help you in understanding the concepts better.
Code Example 1
current_time = datetime.datetime.utcnow()
ten_weeks_ago = current_time - datetime.timedelta(weeks=10)
subjects_within_the_last_ten_weeks = session.query(Subject).filter(
Subject.time > ten_weeks_ago).all()
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