Accepts a DateTime, DateOnly, or legacy Date object as input. Returns an object of the same type that corresponds to the first day of the year that contains the specified date.
Example
SELECT OrderDate as "date", year_first_day(OrderDate) as "year_first_day" FROM "dates_sample_data";
| date | year_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 | 2015-01-01 00:00:00 |
| 2016-01-21 23:59:59 | 2016-01-01 00:00:00 |
| 2015-10-31 23:59:59 | 2015-01-01 00:00:00 |
| 2015-12-03 00:00:00 | 2015-01-01 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 |