从一个城市获取客户的百分比

Question

我想获取居住在某些城市的注册客户的百分比。

目前我有这个

SELECT 
COUNT(city)/Count(CustID) * 100 AS percent, city 
FROM customer 
GROUP BY City 

目前，它提供了100％的每一行的结果。
我很想念这里的东西。我如何解决我的查询？

Answer 1

你需要得到客户的总数在一个单独的子查询：

SELECT COUNT(city)/(SELECT Count(CustID) FROM Customer) * 100 AS percent, city 
FROM customer 
GROUP BY City 

，或者使用CROSS JOIN：

SELECT 
COUNT(city)/x.cnt * 100 AS percent, city 
FROM customer 
CROSS JOIN (SELECT Count(CustID) AS cnt FROM Customer) AS x 
GROUP BY City 

Answer 2

尝试这个

SELECT 
COUNT(city)/(SELECT Count(CustID) FROM Customer) * 100 AS percent, city 
FROM customer c 
GROUP BY City 

在数数