SQL查询选择下订单最多的客户

Question

我想选择下订单最多的客户:

我有 2 个表:

CREATE TABLE customers(
customerid INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
NAME CHAR(50) NOT NULL,
address CHAR(100) NOT NULL,
city CHAR(30)NOT NULL
);


CREATE TABLE orders(
orderid INT UNSIGNED NOT NULL,
customerid INT UNSIGNED NOT NULL,
);

这就是我想要做的:

SELECT customers.customerid, customers.name,orders.orderid, COUNT(customerid) 
AS CostumerCount 
FROM customers 
INNER JOIN orders 
ON customers.customerid=orders.orderid; 

我该怎么做？

Answer 1

既然您使用的 RDBMS 不一定，那么让我假设您使用的是 MySQL，并且您正在寻找具有最高订单数:

SELECT 
  customers.customerid, 
  customers.name,
  COUNT(orders.orderid) AS Orderscount
FROM customers 
INNER JOIN orders ON customers.customerid = orders.customerid 
GROUP BY customers.customerid, 
         customers.name
ORDER BY Orderscount DESC
LIMIT 1;