Question

我需要创建一个SQL语句来获取以下信息：多个表中的ISBN，Quantity，OrderTotal，FirstName，LastName，PhoneNumber和StreetAddress。

以下是我到目前为止提供的两个查询，它们为我提供了所需的信息：

CustomerInfo

SELECT c.CustomerID, c.FirstName, c.LastName, c.PhoneNumber, a.StreetAddress
FROM Customers AS c, Address AS a
WHERE c.CustomerID = a.CustomerID;

订单信息

SELECT o.CustomerID, o.OrderTotal, i.ISBN, i.Quantity
FROM Orders AS o, OrderItems as i
WHERE o.OrderID = i.OrderID;

CombinedQuery 这不起作用!!!

SELECT c.FirstName, c.LastName, c.PhoneNumber, c.StreetAddress, o.OrderTotal, o.ISBN, o.Quantity
FROM CustomerInfo as c, OrderInfo as o
WHERE c.CustomerID = o.CustomerID;

如何将前两个查询加入到一个查询中，该查询将提供第三个查询应提供的相同信息？

Answer 1

CustomerId中没有OrderInfo字段。你需要所有三个表

SELECT c.FirstName, c.LastName, c.PhoneNumber, c.StreetAddress,
       oi.OrderTotal, oi.ISBN, oi.Quantity
FROM (Customers as c INNER JOIN
      Orders AS o
      ON c.CustomerID = o.CustomerID
     ) INNER JOIN
     OrderItems as oi
     ON o.OrderID = oi.OrderID;

您还需要使用join子句学习正确的on语法。 where子句中的隐式连接已过时，表达性较差，更容易出错。

Answer 2

SELECT c.CustomerID, c.FirstName, c.LastName, c.PhoneNumber, 
a.StreetAddress, 
o.CustomerID, o.OrderTotal, 
i.ISBN, i.Quantity
FROM Customers AS c, Address AS a, Orders AS o, OrderItems as i
WHERE o.OrderID = i.OrderID;
AND c.CustomerID = a.CustomerID
AND c.CustomerID = o.CustomerID;

尝试将其作为一个大查询而不是两个然后将它们组合起来。这将把所有四个表连接在一起。

MS-Access中的子查询

2 个答案: