mysql查询统计当天，本周，本月数据（time字段为时间戳格式）

        $day_start = date('Y-m-d 00:00:00', time());
        $week_start = date('Y-m-d 00:00:00', strtotime('last day this week'));
        $month_start = date('Y-m-01 00:00:00', time());
        $end = date('Y-m-d H:i:s', time());

        $sql_day = 'SELECT COUNT(1) FROM '.self::$tbl_user_log.' WHERE `time` >= UNIX_TIMESTAMP( "'.$day_start.'" ) AND `time` <= UNIX_TIMESTAMP( "'.$end.'" )';
        $sql_week = 'SELECT COUNT(1) FROM '.self::$tbl_user_log.' WHERE `time` >= UNIX_TIMESTAMP( "'.$week_start.'" ) AND `time` <= UNIX_TIMESTAMP( "'.$end.'" )';
        $sql_month = 'SELECT COUNT(1) FROM '.self::$tbl_user_log.' WHERE `time` >= UNIX_TIMESTAMP( "'.$month_start.'" ) AND `time` <= UNIX_TIMESTAMP( "'.$end.'" )';