JOIN用法,登录网站的月统计次数

网站的用户登录网站的月统计次数，每天登录多次算一次

--VIEW DWUSER.LOGIN_MYONSTAR_MONTH:  供应商逻辑
  select count(*) from (--直接COUNT出来月访问量
   select trunc(OCCUR_DATE),user_id,count(user_id) from T_SODW_ACTIVITY_LOG --每一个人每天的一条记录
   where  usertype = 'subscriber'
   AND result = 'Success'
   AND occur_date>=to_date('2011-08-01','YYYY-MM-DD')
   and OCCUR_DATE<TO_DATE('2011-09-01','YYYY-MM-DD')
   group by trunc(OCCUR_DATE),user_id order by trunc(OCCUR_DATE) desc
  )

VIEW DWUSER.LOGIN_MYONSTAR_MONTH:       

 select substr(tab.aday,1,7),sum(E_mail) from(--让每一天的访问量相加成为总量             
   SELECT  TO_CHAR (OCCUR_DATE, 'yyyy-mm-dd') aday,COUNT (DISTINCT user_id) E_mail --先取每天的访问量
      FROM   T_SODW_ACTIVITY_LOG
      WHERE   usertype = 'subscriber'
      AND TO_CHAR (OCCUR_DATE, 'mm') <>
      TO_CHAR (SYSDATE, 'mm')
      AND user_id LIKE '%@%'
      AND result = 'Success'
      GROUP BY   TO_CHAR (OCCUR_DATE, 'yyyy-mm-dd')
 ) tab
 group by substr(tab.aday,1,7)

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JOIN用法在多表之间连接

SELECT t1.*
     FROM  t1 LEFT JOIN t2
ON t1.order_number = t2.order_number
INNER JOIN t3
ON t2.order_number_seq = t3.order_number_seq