MySQL日期分组统计

-- 按天统计
SELECT date_format(send_time,'%Y-%m-%d') as date FROM 表 ORDER BY date;
-- 按周统计
SELECT date_format(send_time,'%Y-%u') as date FROM 表 ORDER BY date;
-- 按月统计
SELECT date_format(send_time,'%Y-%m') as date FROM 表 ORDER BY date;