Truncates a datetime value to the year.
tis a datetime structure or a timestamp
t is a
DateTime structure or a timestamp, then
t rounded to the nearest preceding year; effectively, it sets the month, day, hour, minute, second, and millisecond parts to zero or one (as appropriate).
TruncToYear(t) is a
DateTime structure or a timestamp if
t ≔ datetime(1985, 06, 07, 18, 20, 52, 137)
date.year: 1985 date.month: June date.day: 7 time.hour: 18 time.minute: 20 time.second: 52 time.millisecond: 137
date.year: 1985 date.month: January date.day: 1 time.hour: 0 time.minute: 0 time.second: 0 time.millisecond: 0