系人总数公 fangshi1as方式, th yuefen as月份, count(distinct(th duifang) th fangshi, th yuefen; 月份|联系人总数 sq1> select th fangshi as平均人数, count( th huifang)/ count( distinct( th yuefen) 联系人平均数 平均人数 联系人平均数 结果 33分析个人语音通信中每个月主叫和被叫通信总时长及平均时 长;SQL语句: select th fangshi as方式 th yuefen as月份, sum(th shichang)as 通信总时(秒 )"from tonghua group by th fangshi, th yuefen select th fangshi as方式,sum(th shichang )/count(distinct(th yuefen)as"月平均时 长(秒” from tonghua group by th fangshi 结 果9 结果： 3.3 分析个人语音通信中每个月主叫和被叫通信总时长及平均时 长；SQL 语句：select th_fangshi as 方式,th_yuefen as 月份,sum(th_shichang) as " 通信总时(秒)" from tonghua group by th_fangshi,th_yuefen; select th_fangshi as 方式,sum(th_shichang)/count(distinct(th_yuefen)) as "月平均时 长(秒)" from tonghua group by th_fangshi; 结果：