mysql 获取某个时间段内每天的数据

SELECT 
   　　dayTb.cday '日期' 
    ,IFNULL(tNumTb.num,0) '订单数'
FROM (
    SELECT @cdate := DATE_ADD(@cdate, INTERVAL +1 DAY) cday
		FROM( SELECT @cdate := DATE_ADD('2021-03-01', INTERVAL -1 DAY) FROM order_order ) t0
		WHERE date(@cdate) <= DATE_ADD('2021-03-31', INTERVAL -1 DAY)
) as  dayTb

LEFT JOIN(
    SELECT DATE(oo.end_at) cday,count(DISTINCT oo.id) num FROM order_order oo left join member_user as mu on oo.user_id = mu.id 
        WHERE oo.end_at >='2021-03-01'
	and mu.parent_service=2
        GROUP BY cday
) tNumTb ON tNumTb.cday = dayTb.cday

　　

【转载】：https://www.jianshu.com/p/a63526962139