MySQL Query GROUP BY day / month / year

Method I :
SELECT count('id') as cnt,order_status,order_date FROM `product_order` 
group by MONTH(order_date) 
Method II :
SELECT count('id') as cnt,order_status,order_date FROM `product_order` 
group by DATE_FORMAT(order_date, '%m')
Method III:
SELECT SQL_NO_CACHE YEAR(record_date), MONTH(record_date), COUNT(*) FROM stats 
GROUP BY YEAR(record_date)*100 + MONTH(record_date)

SELECT YEAR(date_column), MONTH(date_column), COUNT(*)
FROM date_table
GROUP BY DATE_FORMAT(date_column, '%Y%m')