Question

这是相关表格

movie(id, title, relYear, category, runTime, director,
studioName, description, rating)

actor(aID, fName, surname, gender)

stars(movieID, actorID)

movGenre(movieID, genre)

我只是想返回使用子查询“ Michael Fassbender”担任主角的电影...如果是这种情况，电影中的“ id”是指电影ID，而不是演员ID。我可以做

SELECT title, category
FROM movie 
WHERE 'id' =(SELECT 'aID'
             FROM actor
             WHERE fName='Michael' and surname='Fassbender')

有没有一种方法可以不使用任何联接？

Answer 1

您可以将Correlated Subquery与Exists()一起使用

SELECT m.title, m.category
FROM movie AS m
WHERE EXISTS (SELECT 1
              FROM stars AS s 
              JOIN actor AS a ON a.aID = s.actorID
              WHERE a.fName = 'Michael' AND 
                    a.surname = 'Fassbender' AND
                    s.movieID = m.id)

以上解决方案仍以某种方式（在子查询中）利用JOIN。完全不使用Join的解决方案可以是：

SELECT title, category
FROM movie
WHERE id IN (SELECT movieID 
             FROM stars 
             WHERE actorID IN (SELECT aID 
                               FROM actor 
                               WHERE fName = 'Michael' AND 
                                     surname = 'Fassbender'))

PS 。除非这是一些技巧/硬件，否则我强烈建议不要在实际应用中使用此查询。

Answer 2

SELECT DISTINCT m.title, m.category
FROM movie 
INNER JOIN stars s
ON s.movieID = m.id
INNER JOIN actors a
ON s.actorID = a.aID
   AND a.fName='Michael' 
   AND a.surname='Fassbender'

mysql使用没有连接的子查询

2 个答案: