mysqlで曜日名で注文する方法、つまり、日曜日、月曜日、火曜日、水曜日など
SELECT
DAYNAME(dl.bookingDate) AS dayName, COUNT(dg.idDiary) AS totalBooked
FROM
diary_list dl, diary_group dg
WHERE
dl.idDiary = dg.idDiary AND dg.idService != 0 AND dl.status = 3
GROUP BY
dayName
ORDER BY
dayName ???