mysql - 使用自定义列进行 SQL SELECT 查询，然后按列求和并分组

Question

尝试基本上将两个查询合而为一并将它们连接起来:

第一个查询:

SELECT y.exchange
      ,  k.close * k.volume money_volume  
 FROM symbols y
JOIN stocks k 
    ON y.id = k.id  
 WHERE k.t = '20160323'  
  ORDER 
    BY money_volume DESC  

第二个查询:

SELECT SUM(money_volume) AS money_volume_sum  
  FROM [table just made above]  
 GROUP 
    BY symbols.exchange  

感谢您的审阅，如果您有一种有效的方法将这两个查询合并到一个 SELECT 查询中，请告诉我。

干杯。

Answer 1

SELECT SUM(money_volume) AS money_volume_sum  
FROM (
    SELECT symbols.exchange, stocks.close * stocks.volume AS money_volume  
    FROM symbols  
    JOIN stocks ON symbols.id = stocks.id  
    WHERE stocks.t = '20160323'  
    ORDER BY money_volume DESC  
) t
GROUP BY exchange