Question

我正在学习SQL，并且我编写了一个返回所有Fords所有者的查询。如何修改查询，使其不归还拥有福特和Ferarri的任何人？

SELECT  DISTINCT Owns.Pid
FROM (Person INNER JOIN Owns ON Person.Pid= Owns.Pid) INNER JOIN Car ON Owns.Cid=Car.Cid
WHERE Car.Manufacturer = 'Ford'

添加了：

我尝试了以下代码，看看我是否可以只生产没有Ferarris的人，但它会生成一个空白的数据表。有什么想法吗？

SELECT  DISTINCT Owns.Pid
FROM (Person INNER JOIN Owns ON Person.Pid= Owns.Pid) INNER JOIN Car ON Owns.Cid=Car.Cid
WHERE NOT EXISTS
(SELECT  Owns.Pid
FROM (Person INNER JOIN Owns ON Person.Pid= Owns.Pid) INNER JOIN Car ON Owns.Cid=Car.Cid
WHERE Car.Manufacturer = 'Ferarri' )

Answer 1

由于这是标记的作业，这里有一些提示：

查找拥有法拉利的所有人的ID（应与原始查询几乎相同）
在子查询（或联接）中使用此查询以将其从原始查询中排除

Answer 2

SELECT 

  FORDOWNERS.PID

FROM 

  (SELECT  DISTINCT Owns.Pid
  FROM (Person INNER JOIN Owns ON Person.Pid= Owns.Pid) INNER JOIN Car ON Owns.Cid=Car.Cid
  WHERE Car.Manufacturer = 'Ford') AS FORDOWNERS

INNER JOIN 

  (SELECT  DISTINCT Owns.Pid
  FROM (Person INNER JOIN Owns ON Person.Pid= Owns.Pid) INNER JOIN Car ON Owns.Cid=Car.Cid
  WHERE Car.Manufacturer = 'Ferrari') AS FERRARIOWNERS

ON FORDOWNERS.PID = FERRARIOWNERS.PID

或者像这样

SELECT 

  OWNS.PID

FROM 

  Person INNER JOIN Owns ON Person.Pid= Owns.Pid INNER JOIN Car ON Owns.Cid=Car.Cid
  WHERE Car.Manufacturer = 'Ford'
  AND OWNS.PID IN (SELECT  DISTINCT Owns.Pid
                   FROM (Person INNER JOIN Owns ON Person.Pid= Owns.Pid) INNER JOIN Car ON Owns.Cid=Car.Cid
                   WHERE Car.Manufacturer = 'Ferrari')

如何在SQL中展示不拥有法拉利的福特车主

2 个答案: