MySQL GROUP BY and HAVING子句

Question

我正在尝试编写一个脚本，以显示至少有两个客户的每个城市的名称，以及该城市的客户数量。

这就是我所拥有的，但我不知道如何获得客户的数量。我说得对吗？

SELECT CONCAT (FName,' ',LName) AS Customers, city 
FROM Customer
GROUP BY City
HAVING COUNT(CID) >= 2

Answer 1

使用计数(*)

 SELECT city , count(*)
 FROM Customer 
 GROUP BY City HAVING COUNT(*) >= 2

Answer 2

正如你从这个例子中看到的：

SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders FROM (Orders
INNER JOIN Employees
ON Orders.EmployeeID=Employees.EmployeeID)
GROUP BY LastName
HAVING COUNT(Orders.OrderID) > 10;

必须在select中输入COUNT (CID)