ysq1> select th fangshi as方式, th yuefen as月份, count( th xuhao)as总数from by th fangshi, th 主主被被被 11 rows in set (0.00 sec) mysql> select th fangshi as H=t, count (th xuhao)/count(distinct (th yuefen))a 均通话次数from hua group by th fangshi 平均通话次数 41.4000 3.2分析个人语音通信中每个月主叫和被叫联系人总人数及平均 人数;SQL语句: select th fangshi as方式 th yuefen as月 份 count(distinct(th duifang)as联系人总数 from tonghua group by th fangshi,th yuefen select th fangshi as平均人数 count( th duifang)count(distinct(th yuefen)as联系 人平均数 from tonghua group by th fangshi8 3.2 分析个人语音通信中每个月主叫和被叫联系人总人数及平均 人数； SQL 语句： select th_fangshi as 方 式 ,th_yuefen as 月 份 ,count(distinct(th_duifang)) as 联 系 人 总 数 from tonghua group by th_fangshi,th_yuefen; select th_fangshi as 平均人数,count(th_duifang)/count(distinct(th_yuefen)) as 联系 人平均数 from tonghua group by th_fangshi;