MySQL [test]> SELECT * FROM fechas;
+----+---------------------+
| id | fecha |
+----+---------------------+
| 1 | 2018-10-01 00:00:00 |
| 2 | 2018-10-02 00:00:00 |
| 3 | 2018-10-06 00:00:00 |
| 4 | 2018-10-07 00:00:00 |
| 5 | 2018-10-10 00:00:00 |
| 6 | 2018-10-13 00:00:00 |
+----+---------------------+
6 rows in set (0.00 sec)
MySQL [test]> SELECT * FROM fechas WHERE DAYOFWEEK(fecha) = 7;
+----+---------------------+
| id | fecha |
+----+---------------------+
| 3 | 2018-10-06 00:00:00 |
| 6 | 2018-10-13 00:00:00 |
+----+---------------------+
2 rows in set (0.01 sec)
MySQL [test]>