此查询中缺少什么 'keyword'？

Question

这是我的；

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;

当我输入这个时，数据库在第四行抛出 "missing keyword" 错误。你能告诉我我错过了什么吗

Answer 1

JOIN 是使用 ON 子句执行的，而不是 WHERE:

...
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'    
...

after join 后出现的 WHERE 子句应该像在查询中那样使用。

除了 JOIN 的问题之外，使用 SUM 也没有分组问题。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;

SUM 函数的使用意味着 GROUP BY 子句。所选的每个不属于 SUM 聚合函数的列都必须出现在 GROUP BY 子句中。

Answer 2

您需要使用 ON，而不是第 5、7 和 9 行中的 WHERE。您也在使用函数 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;

此查询中缺少什么 'keyword'？

What is 'keyword' is missing from this query?

sql

oracle

keyword