`month_first_day({date})`

Accepts a DateTime, DateOnly, or legacy object as input. Returns an object of the same type that corresponds to the first day of the month that contains the specified date.

Example

1SELECT OrderDate as "date", month_first_day(OrderDate) as "month_first_day" FROM "dates_sample_data";

date	month_first_day
2015-01-21 15:30:00	2015-01-01 00:00:00
2015-01-21 00:00:00	2015-01-01 00:00:00
2015-01-31 10:00:30	2015-01-01 00:00:00
2015-02-03 15:30:00	2015-02-01 00:00:00
2016-01-21 23:59:59	2016-01-01 00:00:00
2015-10-31 23:59:59	2015-10-01 00:00:00
2015-12-03 00:00:00	2015-11-01 00:00:00
2016-01-11 03:30:00	2016-01-01 00:00:00
2016-01-11 03:30:00	2016-01-01 00:00:00