Question

由于这是我在这样的问题中找到的最好的页面，我想在这里问这个。我在这里有点困惑。我是SQL语句的初学者，所以我需要你的帮助。我有三张桌子：

产品
product_category
product_to_category

我向您展示了导出的SQL文件，因此您可以得到：

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;

CREATE TABLE IF NOT EXISTS `product` (
  `productID` int(6) NOT NULL AUTO_INCREMENT,
  `productTitle` varchar(255) NOT NULL,
  `productDescription` text NOT NULL,
  `productPrice` double NOT NULL DEFAULT '0',
  `productQuantity` int(5) NOT NULL,
  PRIMARY KEY (`productID`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;

INSERT INTO `product` (`productID`, `productTitle`, `productDescription`, `productPrice`, `productQuantity`) VALUES
(1, 'Chlor 5L', 'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. \r\n\r\nDuis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. \r\n\r\nUt wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. \r\n\r\nNam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. \r\n\r\nDuis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis. ', 14.95, 50),
(2, 'Chlor 15L', 'Mit diesem Kanister kommen Sie etwa 27.000 Liter aus.', 50, 13),
(3, 'Chlor 20L', 'Mit diesem Kanister kommen Sie etwa 37.000 Liter aus.', 60, 2),
(4, 'Chlor 25L', 'Mit diesem Kanister kommen Sie etwa 47.000 Liter aus.', 79, 11),
(5, 'Kieselgur 50kg', 'Eine menge Kieselgur zum säubern.', 69.99, 9);


CREATE TABLE IF NOT EXISTS `product_category` (
  `categoryID` int(3) NOT NULL AUTO_INCREMENT,
  `categoryName` varchar(255) NOT NULL,
  `categoryDescription` text NOT NULL,
  PRIMARY KEY (`categoryID`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;


INSERT INTO `product_category` (`categoryID`, `categoryName`, `categoryDescription`) VALUES
(1, 'Schwimmbecken', 'Hier finden Sie alle Produkte rund um das Thema Schwimmbecken.'),
(2, 'Whirlpool', 'Hier finden Sie alle Produkte rund um das Thema Whirlpools.'),
(3, 'Sauna', 'Hier finden Sie alle Produkte rund um das Thema Sauna.'),
(4, 'Infrarot', 'Hier finden Sie alle Produkte rund um das Thema Infrarotkabinen.');


CREATE TABLE IF NOT EXISTS `product_to_category` (
  `categoryID` int(3) NOT NULL,
  `productID` int(6) NOT NULL,
  `productAddedTime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`categoryID`,`productID`),
  KEY `productID` (`productID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT INTO `product_to_category` (`categoryID`, `productID`, `productAddedTime`) VALUES
(1, 1, '2011-11-27 13:57:12'),
(1, 2, '2011-11-27 13:57:12'),
(1, 3, '2011-11-27 13:57:12'),
(1, 4, '2011-11-27 13:57:12'),
(1, 4, '2011-11-27 13:57:12'),
(2, 1, '2011-11-27 13:57:12');

ALTER TABLE `product_to_category`
  ADD CONSTRAINT `product_to_category_ibfk_2` FOREIGN KEY (`categoryID`) REFERENCES `product_category` (`categoryID`),
  ADD CONSTRAINT `product_to_category_ibfk_3` FOREIGN KEY (`productID`) REFERENCES `product` (`productID`);

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

所以，我想做的是：我想获得所有产品的所有信息。我想按类别将它们分组在一页上。另外我想展示每个类别的产品数量。我不知道，怎么做。我使用此声明获得了每个类别的正确数量的产品，但仅限于产品。但是我想要所有类别的所有产品的产品的信息，希望我说明了我的观点，否则你可能会再次询问。我试着解释一下。

SELECT COUNT(ptc.productID) AS productCount, pc.categoryName, p.productTitle, p.productPrice 
FROM product_category pc
JOIN product_to_category ptc ON pc.categoryID = ptc.categoryID
JOIN product p ON ptc.productID = p.productID
GROUP BY pc.categoryName

我希望你有答案...

我想做的是这样的概述：

Schwimmbecken (5 products)    
 - Chlor 5L (14.95)
 - Chlor 15L (50.00)
 - Chlor....

Whirlpool (1 product)  
 - Chlor 5L (14.95)

希望这足以表明你......

Answer 1

我认为你很接近，但我会'开始'产品或类别我将从产品开始，链接到product_category，然后转到catergory，例如类似的东西：

SELECT COUNT(p.productID) AS productCount, c.categoryName, p.productTitle, p.productPrice 
FROM product p 
JOIN product_to_category ptc ON ptc.categoryID = p.productID
JOIN category c ON ptc.catgeory_id = c.categoryID 
ORDER BY c.categoryName

从此开始，检查结果，然后根据需要添加分组。

Answer 2

使用（更正版本）

SELECT DISTINCT
c.categoryName || '(' || c.cnt || ' products)' title,
x.productTitle || '(' || x.productPrice || ')' productinfo
FROM
(
select 
pc.categoryid, 
pc.categoryName, 
count(distinct p2c.productID) cnt 
from product_category pc 
INNER JOIN product_to_category p2c ON p2c.categoryid = pc.categoryid
group by pc.categoryid, pc.categoryName
) c
INNER JOIN 
(
SELECT DISTINCT
ptc.categoryid, 
p.productTitle, 
p.productPrice
FROM product p
INNER JOIN product_to_category ptc ON p.productID = ptc.productID
) x ON x.categoryid = c.categoryid
ORDER BY 1, 2

除了一件事之外，这将给你要求的东西 - title会像在相应类别中有产品一样经常重复......那部分不能通过SQL本身来处理，你会必须在你的代码中处理它......

编辑 - 根据评论：

上面的选择在两个SELECT之间进行内部连接...首先每个类别获得一行加上该类别中的产品数量...第二个获得每个类别的所有产品...这些通过categoryid连接...

尝试使用您的示例数据并获得以下结果：

TITLE                   PRODUCTINFO

Schwimmbecken(4 products)   Chlor 15L(50)
Schwimmbecken(4 products)   Chlor 20L(60)
Schwimmbecken(4 products)   Chlor 25L(79)
Schwimmbecken(4 products)   Chlor 5L(14,95)
Whirlpool(1 products)       Chlor 5L(14,95)

BTW：您的示例数据似乎已关闭... productId 1中有两次categoryID 4，而productID 5未在任何地方使用...

按类别获取产品的所有信息 - SQL？

2 个答案: