select  wk.MINDATE FIRST_LOGIN
        ,count(wk.MEM_CODE) MEMBER_CNT
  from  (
    select  a.MEMBER_CODE MEM_CODE
            ,SUBSTR(MIN(a.LOGIN_DATETIME),1,10) MINDATE
      from  ACCESS_LOG a
     group by SUBSTR(a.MEMBER_CODE,1,10)
     ) wk
 where  wk.MINDATE >= '2023-08-01'
   and  wk.MINDATE <  '2023-09-01'

 group by wk.MINDATE
 order by wk.MINDATE