[英]SQL count doesn't work with null
SELECT
customers.customerNumber, customers.customerName,
customers.state, customers.city,
COUNT(orders.customerNumber) AS OrdSum
FROM
customers
INNER JOIN
orders ON customers.customerNumber = orders.customerNumber
WHERE
(customers.state <> 'NY') AND (customers.country = 'USA')
GROUP BY
customers.customerName
ORDER BY customers.customerNumber;
这是我的SQL代码。 具有COUNT的表不会显示具有0值的行。
这是您想要的吗?
SELECT c.customerNumber, c.customerName, c.state, c.city,
COUNT(o.customerNumber) AS OrdSum
FROM customers c LEFT JOIN
orders o
ON c.customerNumber = o.customerNumber
WHERE c.state <> 'NY' AND c.country = 'USA'
GROUP BY c.customerNumber, c.customerName, c.state, c.city
ORDER BY c.customerNumber;
这应该显示纽约的所有客户以及他们的订单数量,即使他们没有订单。 不过我很好奇:如果没有订单,某人怎么会在一个叫customers
的表中?
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