Question

这就是我所拥有的;

SELECT c.customerFN, c.customerEmail, p.productName, 
SUM(p.unitsonstock + p.unitsordered) AS "All Units"
FROM customer c
INNER JOIN order o
 WHERE c.customerID=o.customerID
INNER JOIN orderDetails d 
 WHERE o.orderID=d.orderID
INNER JOIN product p
 WHERE p.productCode=l.productCode
WHERE orderDate <= '2015-03-15'
 ORDER BY productName;

当我输入此数据库时，数据库会在第四行引发“缺少关键字”错误。你能告诉我我失踪了吗

Answer 1

而不是第5,7和9行中的WHERE，您需要使用ON。您还使用了函数SUM，但没有GROUP BY。像这样更改您的查询：

SELECT c.customerFN, c.customerEmail, p.productName, 
SUM(p.unitsonstock + p.unitsordered) AS "All Units"
FROM customer c
INNER JOIN order o
ON c.customerID=o.customerID
INNER JOIN orderDetails d 
ON o.orderID=d.orderID
INNER JOIN product p
ON p.productCode=l.productCode
WHERE orderDate <= '2015-03-15'
GROUP BY c.customerFN, c.customerEmail, p.productName
ORDER BY p.productName;

Answer 2

JOIN使用ON子句执行，而不是WHERE执行：

...
FROM customer c
INNER JOIN order o ON c.customerID=o.customerID
INNER JOIN orderDetails d ON o.orderID=d.orderID
INNER JOIN product p ON p.productCode=d.productCode
WHERE orderDate <= '2015-03-15'    
...

加入后来自的WHERE子句应该像在查询中一样使用。

除了JOIN的问题之外，使用SUM而没有分组也存在问题。你可能想要这样的东西：

SELECT c.customerFN, c.customerEmail, p.productName, SUM(p.unitsinstock + p.unitsordered) AS "All Units" FROM customer c INNER JOIN order o ON c.customerID=o.customerID INNER JOIN orderDetails d ON o.orderID=d.orderID INNER JOIN product p ON p.productCode=d.productCode WHERE orderDate <= '2015-03-15' GROUP BY customerFN, customerEmail, productName ORDER BY p.productName;

使用SUM函数意味着GROUP BY子句。选择的每个列都不属于SUM等聚合函数的一部分，必须出现在GROUP BY子句中。

此查询缺少什么'keyword'？

2 个答案: