family_dinner.sql

UPDATE meals SET transfers = FALSE WHERE hall_id != 'CM';
UPDATE meals SET transfers = TRUE WHERE hall_id != 'CM' AND date >= '2021-09-01';
UPDATE meals SET transfers = FALSE WHERE hall_id != 'CM' AND name = 'Dinner' AND date IN ('2021-11-07', '2021-10-31', '2021-10-24', '2021-10-17', '2021-10-10', '2021-10-03', '2021-09-26', '2021-09-19', '2021-09-12');

find_sundays.py

import datetime
start_date = datetime.date(2021, 9, 8)
date = datetime.date(2021, 11, 7)
sundays = []
while date > start_date:
    sundays.append(date.strftime('%Y-%m-%d'))
    date -= datetime.timedelta(days=7)

print(sundays)