Question

对于给定的数据库

Product(maker, model, type)
PC(code, model, speed, ram, hd, cd, price)

问题是： 找到能够生产RAM最低的PC和具有最低RAM的PC中最高速处理器的打印机制造商。结果集：制造商。

让我们分开查询！

找到也生产PC的打印机制造商

从产品Group By制造商中选择DISTINCT制造商，输入HAVING类型 IN（'打印机'，'PC'）

我认为这是错误的，因为IN（'Printer'，'PC'）就像OR not AND

内存最低的PC

SELECT模型，速度FROM pc WHERE ram =（SELECT MIN（ram）FROM pc）as lowestRam

RAM率最低的PC中的最高速处理器

WHERE
lowestRam.speed=(SELECT MAX(speed) FROM pc WHERE ram=(SELECT MIN(ram) FROM pc))

查询自己！

SELECT DISTINCT maker FROM
(SELECT DISTINCT model,speed FROM pc WHERE ram=(SELECT MIN(ram) FROM pc)) as lowestRam
INNER JOIN product 
ON product.model=lowestRam.model
WHERE
lowestRam.speed=(SELECT max(speed) FROM pc WHERE ram=(SELECT MIN(ram) FROM pc))
Group By maker,type HAVING type IN( 'Printer' ,'PC')

不幸的是，当我在检查网站上提交查询时，会产生1个额外的错误结果：（

问题来自Link。查询验证有2个步骤。第二步仅显示用户和正确结果之间的差异：（

Answer 1

这可以解决您的问题：

select distinct maker from Product
where type = 'Printer' and maker in (select maker
from Product join PC on Product.model = PC.model
where ram = (select min(ram) from PC) and speed = (select max(speed) from PC 
where ram = (select min(ram) from PC)))

Answer 2

我的查询看起来是正确的（虽然有点过于复杂）。如果您可以提供样本数据和“额外的错误结果”，那么跟踪问题会更容易。

这是我查询的简化版本：

SELECT DISTINCT p1.maker
FROM product p1, pc
WHERE  p1.model = pc.model
   AND pc.speed = (SELECT MAX (speed)
                   FROM pc
                   WHERE ram = (SELECT MIN (ram) FROM pc))
   AND EXISTS (SELECT 1 from product p2 where maker = p1.maker and p2.type = 'Printer')

Answer 3

试试这个：

    SELECT p.maker 
FROM
(
SELECT *,DENSE_RANK() OVER (ORDER BY ram ASC,speed DESC) AS Rnk
FROM Product p
INNER JOIN (SELECT maker
            FROM Product 
            WHERE type IN ('PC','printer')
            GROUP BY maker
            HAVING COUNT(DISTINCT type)=2
           )p1
ON p1.maker = p.maker
INNER JOIN PC  
ON PC.model = p.model
)t
WHERE Rnk=1

Answer 4

SELECT  DISTINCT maker
  FROM product
 WHERE model IN (
    SELECT p.model
      FROM pc p JOIN printer r 
                  ON (p.ram =(SELECT min(ram) FROM pc) AND  
                      p.speed=(SELECT max(speed) FROM pc WHERE ram = 
                              (SELECT min(ram) FROM pc))
                     )
                 )

Answer 5

 SELECT DISTINCT maker FROM    
 (SELECT DISTINCT model,speed FROM pc WHERE ram=(SELECT MIN(ram) FROM pc)) as lowestRam
 INNER JOIN product 
       ON product.model=lowestRam.model AND
 lowestRam.speed=(SELECT max(speed) FROM pc WHERE ram=(SELECT MIN(ram) FROM pc))
 Group By maker HAVING maker IN( SELECT DISTINCT maker FROM Product WHERE type='Printer')

Answer 6

选择不同的制造商从产品，电脑 product.model in （选择型号来自电脑速度在哪里（从掌上电脑组中选择最大（速度））和ram in （从掌上电脑中选择ram（从电脑中选择min（ram））））和product.maker in（从产品中选择制造商，其中type =＆＃39; printer＆＃39;）和Product.model = PC.model

Answer 7

你可以试试这个：

SELECT DISTINCT G.MAKER FROM PC F,PRODUCT G
WHERE 
F.MODEL = G.MODEL
AND F.SPEED=
(
  SELECT MAX(E.SPEED) FROM PC E WHERE E.RAM =
  (
   SELECT MIN(C.RAM) FROM PC C,PRODUCT D WHERE D.MAKER IN 
          (SELECT A.MAKER FROM PRODUCT A,PRINTER B WHERE A.MODEL=B.MODEL)
  )
)

Answer 8

从产品，PC中选择不同的制造商，其中product.model = PC.model和product.type =＆＃39; PC＆＃39;和速度=（从PC中选择max（PC.speed），其中ram =（从PC中选择min（PC.ram）））

value是a和b的类型

8 个答案: