SQL - 以百分比顯示結果

Question

select retention 
, Sum(count(retention)) over(order by retention desc) as Num_Users_Retained 
    from (select player_id 
     , round(init_dtime-create_dtime,0) as retention 
     from player 
    where Trunc(Create_Dtime) >= To_Date('2012-jan-01','yyyy-mon-dd') 
     and init_dtime is not null) 
    Group by retention 
    order by retention 

此查詢顯示兩列：第一列是今年的一天（第0天是1月1日，第259天是今天sep-16），第二列是保留。第0天有428,000個，因爲所有用戶都被保留，第1天有300K（因爲128K人在他們第一天後沒有登錄），並且隨着時間的推移，這個數字一直在減少。我想爲每天的第0天的百分比顯示另一列。是否足夠清楚，還是應該提供更多詳細信息？

Answer 1

select retention 
    , Num_Users_Retained 
    , round(Num_Users_Retained/max(Num_Users_Retained) over() * 100, 2) as perc 
    from (select retention 
      , Sum(count(retention)) over(order by retention desc) as Num_Users_Retained 
     from (select player_id 
        , round(init_dtime-create_dtime,0) as retention 
       from player 
       where Trunc(Create_Dtime) >= To_Date('2012-jan-01','yyyy-mon-dd') 
       and init_dtime is not null 
      ) 
     Group by retention 
     order by retention) 
order by retention