--参与人数:
SELECT count(mobile), FROM_UNIXTIME( time, '%Y年%m月%d' ) t FROM member WHERE id IN ( SELECT max( id ) FROM member GROUP BY mobile ) GROUP BY t
--参与人清单
SELECT mobile,FROM_UNIXTIME(time,'%Y年%m月%d') t FROM member WHERE id IN ( SELECT max( id ) FROM member GROUP BY mobile );