这是我的table。

Financials:
    Date
    CountryID
    ProductID
    Revenue
    Cost

我需要找出每个国家收入前五名的产品。有些产品会多次上市，所以我需要为每个产品的收入加总。

SELECT
  Financials.CountryID,
  Financials.ProductID,
  SUM(Financials.Revenue) AS total
FROM Financials
INNER JOIN (SELECT
  CountryID,
  GROUP_CONCAT (ProductID ORDER BY Revenue DESC) grouped_ID
FROM Financials
GROUP BY CountryID) group_max
  ON Financials.CountryID = group_max.CountryID
  AND FIND_IN_SET(ProductID, grouped_ID) BETWEEN 1 AND 6

GROUP BY Financials.ProductID
ORDER BY Financials.CountryID, total DESC

这就是我目前所知道的。它不起作用。救命啊？
编辑
我一直在用https://sqltest.net/. 请参阅下面的插入命令

CREATE TABLE mysql_test ( 
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
CountryID VARCHAR(30) NOT NULL, 
ProductID VARCHAR(30) NOT NULL,  
Revenue VARCHAR(50), 
cost VARCHAR(50), 
reg_date TIMESTAMP 
); 

CREATE TABLE mysql_test_sql ( 
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
CountryID VARCHAR(30) NOT NULL, 
ProductID VARCHAR(30) NOT NULL,  
Revenue VARCHAR(50), 
cost VARCHAR(50), 
reg_date TIMESTAMP 
); 

INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('1', 'Canada', 'Doe', '20', '5', '2010-01-31 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('2', 'USA', 'Tyson', '40', '15', '2010-02-14 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('3', 'France', 'Keaton', '80', '25', '2010-03-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('4', 'France', 'Joe', '180', '45', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('5', 'France', 'Bill', '30', '6', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('6', 'France', 'Emma', '15', '2', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('7', 'France', 'Joe', '60', '36', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('8', 'France', 'Jammer', '130', '26', '2010-04-25 12:01:01'); 

INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('9', 'France', 'Louis', '350', '12', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('10', 'France', 'dennis', '100', '175', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('11', 'USA', 'zooey', '70', '16', '2010-04-25 12:01:01'); 
INSERT INTO `mysql_test` (`id`, `CountryID`, `ProductID`, `Revenue`, `cost`, `reg_date`) VALUES ('12', 'France', 'Alex', '2', '16', '2010-04-25 12:01:01');