的Oracle SQL - 通過CASE

Question

分組我有以下查詢：

Select Player_Id, 
Pt_Credit As Total_Points 
From Player 
Where Trunc(Create_Dtime) = Trunc(Sysdate) - 90 
And Trunc(Init_Dtime) >= To_Date('2012-sep-1','yyyy-mon-dd') 
Order by Total_Points Desc 

，給了我這樣的結果：

Player_ID  TOTAL_POINTS 
    23452   1500 
    23494   1000 
    30934   500 

等。我想這組結果player_ids到像0-300分，301-600分，601-900分，大於900分團...所以它看起來像這樣的結果：

Point_Level  Count(Player_ID) 
0-300   532 
301-600   444 
601-900   669 
>900    185 

Answer 1

使用CASE ... WHEN

SELECT players.clasification, count(players.player_id) 
FROM (
    SELECT ROWNUM player_id, 
     (ROWNUM + 100) points, 
     CASE 
      WHEN (ROWNUM + 100) BETWEEN 0 AND 300 THEN 
       '0-300' 
      WHEN (ROWNUM + 100) BETWEEN 301 AND 600 THEN 
       '301-600' 
      WHEN (ROWNUM + 100) BETWEEN 601 AND 900 THEN 
       '601-900' 
      ELSE 
       '> 900' 
      END clasification 
    FROM dual 
    CONNECT BY LEVEL <= 1000 
) players 
GROUP BY players.clasification; 

或者在你的榜樣：

SELECT 
    count(player.player_id), 
    player.clasification 
FROM (
    SELECT pl.*, 
     CASE 
      WHEN total_points BETWEEN 0 AND 300 
       THEN '0-300' 
      WHEN total_points BETWEEN 301 AND 600 
       THEN '301-600' 
      WHEN total_points BETWEEN 601 AND 900 
       THEN '601-900' 
      ELSE '> 900' 
     END clasification 
    FROM player pl 
    WHERE 
      TRUNC(Create_Dtime) = TRUNC(SYSDATE) - 90 
     AND TRUNC(Init_Dtime) >= To_Date('2012-sep-1', 'yyyy-mon-dd') 

) 
    Player 
GROUP BY player.clasification; 

Answer 2

Select case 
    when Pt_Credit between 0 and 300 then '0 to 300' 
    when Pt_Credit between 301 and 600 then '301 to 600' 
    when Pt_Credit between 601 and 900 then '601 to 900' 
    else '> 900' 
end Total_Points 
, count(*) 
From Player 
Where Trunc(Create_Dtime) = Trunc(Sysdate) - 90 
And Trunc(Init_Dtime) >= To_Date('2012-sep-1','yyyy-mon-dd') 
Group by case 
    when Pt_Credit between 0 and 300 then 0 
    when Pt_Credit between 301 and 600 then 1 
    when Pt_Credit between 601 and 900 then 2 
    else 3 
end 
Order by Total_Points Desc 

或

Select case 
    when Pt_Credit between 0 and 300 then '0 to 300' 
    when Pt_Credit between 301 and 600 then '301 to 600' 
    when Pt_Credit between 601 and 900 then '601 to 900' 
    else '> 900' 
end Total_Points 
, count(*) 
From Player 
Where Trunc(Create_Dtime) = Trunc(Sysdate) - 90 
And Trunc(Init_Dtime) >= To_Date('2012-sep-1','yyyy-mon-dd') 
Group by cast(Pt_Credit/300 as integer) 
Order by Total_Points Desc