Question

我有一个任务，选择使用sqlzoo.net＆＃34;更多加入＆＃34;指导罗伯特·德尼罗电影，电影片名和年份的所有导演名字。数据库。我设法从数据库中选择了电影标题和所有导演ID。问题是我不知道如何将ID链接到名称...... 如果你接受我发布的代码，你会看到页面右侧的结果。我需要帮助，所以它显示导演NAMES而不是ID。请注意，movie.director键与actor.name匹配！需要以某种方式连接它们。

我使用了这段代码：

select distinct movie.director,movie.title,yr
from movie join casting 
on movie.id=movieid join actor on actor.id=actorid
where movie.id in(select movie.id 
                  from movie join casting on movie.id=movieid 
                  join actor on actor.id=actorid 
                  where actor.name='Robert De Niro')
                  order by yr DESC

Answer 1

假设有一个director表并且movie.director字段与director.id字段匹配，它的外观如何。

select director.name, movie.title, yr 
from   movie 
       join casting on movie.id = casting.movieid 
       join actor on actor.id = movie.actorid 
       join actor as director on director.id = movie.director 
where actor.name='Robert De Niro'
order by yr DESC

Answer 2

你几乎拥有它，你只需要在外部查询中将联接的条件更改为actor以使用movie.director，然后选择actor.name而不是movie.director ：

select distinct actor.name,movie.title,yr
from movie 
join casting on movie.id = movieid 
join actor on actor.id = movie.director
where movie.id in(select movie.id 
                  from movie join casting on movie.id=movieid 
                  join actor on actor.id = actorid 
                  where actor.name='Robert De Niro')
order by yr DESC

由于actor表同时具有actor和director，因此使用表别名可以更容易阅读：

select distinct director.name,movie.title,yr
from movie 
join casting on movie.id = movieid 
join actor AS director on director.id = movie.director
where movie.id in(select movie.id 
                  from movie join casting on movie.id=movieid 
                  join actor on actor.id = actorid 
                  where actor.name='Robert De Niro')
order by yr DESC

使用sqlzoo数据库的SQL问题

2 个答案: