MySQL外键和查询

当我需要来自多个不同表的信息时，我试图理解查询数据的细节

现在我有以下表格

CREATE TABLE `orders` (
  `orderNumber` int(11) NOT NULL,
  `orderDate` date NOT NULL,
  `requiredDate` date NOT NULL,
  `shippedDate` date DEFAULT NULL,
  `status` varchar(15) NOT NULL,
  `comments` text,
  `customerNumber` int(11) NOT NULL,
  PRIMARY KEY (`orderNumber`),
  KEY `customerNumber` (`customerNumber`),
  CONSTRAINT `orders_ibfk_1` FOREIGN KEY (`customerNumber`) REFERENCES `customers` (`customerNumber`)
)

CREATE TABLE `orderdetails` (
  `orderNumber` int(11) NOT NULL,
  `productCode` varchar(15) NOT NULL,
  `quantityOrdered` int(11) NOT NULL,
  `priceEach` double NOT NULL,
  `orderLineNumber` smallint(6) NOT NULL,
  PRIMARY KEY (`orderNumber`,`productCode`),
  KEY `productCode` (`productCode`),
  CONSTRAINT `orderdetails_ibfk_2` FOREIGN KEY (`productCode`) REFERENCES `products` (`productCode`),
  CONSTRAINT `orderdetails_ibfk_1` FOREIGN KEY (`orderNumber`) REFERENCES `orders` (`orderNumber`)
)

CREATE TABLE `products` (
  `productCode` varchar(15) NOT NULL,
  `productName` varchar(70) NOT NULL,
  `productLine` varchar(50) NOT NULL,
  `productScale` varchar(10) NOT NULL,
  `productVendor` varchar(50) NOT NULL,
  `productDescription` text NOT NULL,
  `quantityInStock` smallint(6) NOT NULL,
  `buyPrice` double NOT NULL,
  `MSRP` double NOT NULL,
  PRIMARY KEY (`productCode`),
  KEY `productLine` (`productLine`),
  CONSTRAINT `products_ibfk_1` FOREIGN KEY (`productLine`) REFERENCES `productlines` (`productLine`)
)
CREATE TABLE `customers` (
  `customerNumber` int(11) NOT NULL,
  `customerName` varchar(50) NOT NULL,
  `contactLastName` varchar(50) NOT NULL,
  `contactFirstName` varchar(50) NOT NULL,
  `phone` varchar(50) NOT NULL,
  `addressLine1` varchar(50) NOT NULL,
  `addressLine2` varchar(50) DEFAULT NULL,
  `city` varchar(50) NOT NULL,
  `state` varchar(50) DEFAULT NULL,
  `postalCode` varchar(15) DEFAULT NULL,
  `country` varchar(50) NOT NULL,
  `salesRepEmployeeNumber` int(11) DEFAULT NULL,
  `creditLimit` double DEFAULT NULL,
  PRIMARY KEY (`customerNumber`),
  KEY `salesRepEmployeeNumber` (`salesRepEmployeeNumber`),
  CONSTRAINT `customers_ibfk_1` FOREIGN KEY (`salesRepEmployeeNumber`) REFERENCES `employees` (`employeeNumber`)
)

我想弄清楚的是如何编写查询来查找在两个特定日期之间订购的产品的名称

我一直在看文档和示例，但我似乎不明白。感谢您的帮助。

您需要使用JOIN关键字连接查询表：

/* Get product names ordered between two dates */
select distinct p.productName
from orders o
inner join orderdetails od on od.orderNumber = o.orderNumber
inner join products p on p.productCode = oi.productCode
where o.orderDate >= @startDate AND o.orderDate < @endDate

---

查看文档中的关键词SELECT、INTERNAR JOIN和BETHEN。我已经看过很多例子……但显然遗漏了一些东西。对不起，现在感觉很慢。