mysql 变量定义，以及时间戳字段统计当天数据

set @st=unix_timestamp( DATE_FORMAT(now(),'%Y-%m-%d 0:0:0'));

set @en=unix_timestamp( DATE_FORMAT(now(),'%Y-%m-%d %H:%i:%s')); 

SELECT SUM(o.order_price) FROM dc_order o WHERE o.payment_status = 1 and o.add_time <= @en AND o.add_time >= @st ;