Question

我在http://sqlzoo.net/wiki/Main_Page中练习mysql查询，并遇到了关于连接的特定查询。问题：列出所有电影“朱莉安德鲁斯”中的电影片名和主角。表结构：

movie   : id,title,yr,director,budget,gross -------
actor   :id,name ----------
casting :movieid,actorid,ord

提示：主要演员是演员表中的ord为1的演员我的回答到现在为止：我可以获得所有电影'朱莉安德鲁斯'的电影ID和演员ID。但是使用该结果集，我不知道如何获得不同表格中的标题和名称。 / p>

我的查询到目前为止：

select c1.actorid,c1.movieid 
from casting c1 
where c1.movieid in 
(
   select movieid from casting 
   join  actor on (id=actorid and name='Julie Andrews')
) and c1.ord=1

Answer 1

作为一项学习练习，您应该将查询分解为几个步骤。

步骤1.列出电影标题

SELECT movie.title AS title
FROM movie

第2步。列出朱莉安德鲁斯主演的电影：

SELECT movie.title AS title
FROM movie
JOIN casting
  ON movie.id = casting.movieid
JOIN actor
  ON casting.actorid = actor.id
WHERE actor.name = 'Julie Andrews'

第3步。主角。您可以根据解决问题的方式开始区分解决方案。

如果你想知道主角演员的名字。您的查询看起来像这样：

SELECT actor.name as Name 
FROM casting
JOIN actor
  ON actor.id = casting.actorid
WHERE casting.ord =1

但是，如果你试试这个：

SELECT movie.title AS title
FROM movie
JOIN casting
  ON movie.id = casting.movieid
JOIN actor
  ON casting.actorid = actor.id
WHERE actor.name = 'Julie Andrews'
  AND casting.ord =1;

你只是找到朱莉安德鲁斯是主演的地方。

相反，你需要加入到actors表中（我将添加一些表别名来帮助解释正在连接的表的目的）

SELECT movie.title AS title, LeadActor.name AS LeadActorName
FROM movie
JOIN casting AS JulieCastings
  ON movie.id = JulieCastings.movieid
JOIN actor AS JulieAndrews
  ON JulieCastings.actorid = JulieAndrews.id
JOIN casting AS LeadActorCastings
  ON LeadActorCastings.movieid = movie.id
JOIN actor AS LeadActor
  ON LeadActor.id = LeadActorCastings.actorid
WHERE JulieAndrews.name = 'Julie Andrews'
  AND LeadActor.ord =1;

Answer 2

是的，你应该使用join：

      select c1.actorid, c1.movieid 
        join casting c2 on c2.movieid = c1.movieid
        join  actor a on a.id=c2.actorid
      from casting c1 
        where c1.ord=1 and
              a.name='Julie Andrews'

Answer 3

谢谢你们。我用以下查询解决了它：选择m.title，a.name来自actor一个连接点播c on（a.id = c.actorid和c.ord = 1）连接电影m on（m.id = c.movieid）和m.id in（select来自联盟演员的movieid（id = actorid和name ='Julie Andrews'））

Answer 4

我知道这是一个老话题，但对于仍然像我一样寻求帮助的人，我对Shankar的工作有点用了。希望这会有所帮助。

SELECT title, name 
FROM movie JOIN casting ON (movie.id = casting.movieid) 
           JOIN actor ON (actor.id = casting.actorid)
WHERE movieid IN (SELECT movieid 
                  FROM casting JOIN actor ON (actor.id = casting.actorid)
                  WHERE name = 'Julie Andrews') 
                  AND ord = 1

Mysql Join：如何为多个表使用相同的结果集

4 个答案: