Syntax:
WEEK(date[,mode])

This function returns the week number for date. The two-argument form
of WEEK() enables you to specify whether the week starts on Sunday or
Monday and whether the return value should be in the range from 0 to 53
or from 1 to 53. If the mode argument is omitted, the value of the
default_week_format system variable is used. See
https://mariadb.com/kb/en/server-system-variables/.

URL: https://mariadb.com/kb/en/week/

