WEEKDAY
weekday
Description
Syntax
INT WEEKDAY (DATETIME date)
The WEEKDAY function returns the index value of the working day of the date, that is, 0 on Monday, 1 on Tuesday, and 6 on Sunday.
The parameter is Date or Datetime type
Notice the difference between WEEKDAY and DAYOFWEEK:
          +-----+-----+-----+-----+-----+-----+-----+
          | Sun | Mon | Tues| Wed | Thur| Fri | Sat |
          +-----+-----+-----+-----+-----+-----+-----+
  weekday |  6  |  0  |  1  |  2  |  3  |  4  |  5  |
          +-----+-----+-----+-----+-----+-----+-----+
dayofweek |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
          +-----+-----+-----+-----+-----+-----+-----+
example
mysql> select weekday('2019-06-25');
+--------------------------------+
| weekday('2019-06-25 00:00:00') |
+--------------------------------+
|                              1 |
+--------------------------------+
mysql> select weekday(cast(20190625 as date)); 
+---------------------------------+
| weekday(CAST(20190625 AS DATE)) |
+---------------------------------+
|                               1 |
+---------------------------------+
keywords
WEEKDAY