统计每天、每月每天、每年每月的SQL语句怎么写？

关键就在date_format（）函数的使用。

定义：DATE_FORMAT() 函数用于以不同的格式显示日期/时间数据。
语法：DATE_FORMAT(date,format) date 参数是合法的日期。format 规定日期/时间的输出格式。

案例：

# 统计当天发送数和计费数
select count(0) as sendCount,IFNULL(sum(tstd.task_status=1),0) as billingCount
        from t_sms_task AS tst
                     left join t_sms_task_details AS tstd on tst.id = tstd.task_id 
		where tst.user_id = 2 and date_format(tstd.create_time,'%Y-%m-%d')= date_format(now(),'%Y-%m-%d') 
		
# 统计当月每天发送数和计费数（在月的基础上加天分组）					
 select count(0) as sendCount,IFNULL(sum(tstd.task_status=1),0) as billingCount ,date_format(tstd.create_time,'%Y-%m-%d') as sentTime
        from t_sms_task AS tst
                     left join t_sms_task_details AS tstd on tst.id = tstd.task_id 
		where tst.user_id = 2
		 and date_format(tstd.create_time,'%Y-%m')= DATE_FORMAT( now(), '%Y-%m') GROUP BY sentTime

# 统计每年每月发送数和计费数（在年的基础上加月分组）					
select count(0) as sendCount,IFNULL(sum(tstd.task_status=1),0) as billingCount ,date_format(tstd.create_time,'%Y-%m') as sentTime
        from t_sms_task AS tst
                     left join t_sms_task_details AS tstd on tst.id = tstd.task_id 
		where tst.user_id = 2
		 and date_format(tstd.create_time,'%Y')= DATE_FORMAT( now(), '%Y') GROUP BY sentTime