mysql - 如何在mysql中求和

Question

我有一个关于sql的问题

我有一个表 'Player'，我想要实现的是从 'Player' 创建一个新表 'Level'，我用简单的 sql 完成的 nbPlayerPerLevel

select Level as LevelID,count(*) as nbPlayerPerLevel 
from Player
group by Level 
order by Level DESC 

但困扰我的是我怎么能像以前一样获得 totalPlayer，非常感谢

表:播放器

 playerID  Level 
   1          3  
   2          5
   3          10
   4          3
   5          5 
----> 

表格:级别

LevelID  nbPlayerPerLevel  totalPlayer
10             1              1
5              2              3
3              2              5

Answer 1

假设 totalPlay 是等于或高于给定级别的玩家数量，您需要:

SELECT
  p.Level AS LevelID,
  IFNULL(COUNT(DISTINCT p.playerID),0) AS nbPlayerPerLevel,
  IFNULL(COUNT(DISTINCT pp.playerID),0) AS totalPlayer
FROM
  Player AS p
  LEFT JOIN Player AS pp ON p.Level<=pp.Level
GROUP BY p.Level 
ORDER BY p.Level DESC 

SQLfiddle