WEEKDAYOF returns the day of the week as a number between 0-6 (Sunday 0, Monday 1, and so on) for the date specified by the
date_string. If
input_format is not provided, the default keyword
DELIM_M_D_Y will be used.
WEEKDAYOF("08312000", MMDDYYYY) returns the number 4, since Thursday is the 4th day of the week.