曜日つきのSQLの書き方

SELECT 
    DATE(created_at) AS '日付', 
    COUNT(id) AS '登録数',
    CASE DAYOFWEEK(created_at)
        WHEN 1 THEN '日'
        WHEN 2 THEN '月'
        WHEN 3 THEN '火'
        WHEN 4 THEN '水'
        WHEN 5 THEN '木'
        WHEN 6 THEN '金'
        WHEN 7 THEN '土'
    END AS '曜日'
FROM 
    users
WHERE 
    created_at >= CURDATE() - INTERVAL 30 DAY
GROUP BY 
    DATE(created_at), DAYOFWEEK(created_at)
ORDER BY 
    DATE(created_at);