Question

所以，我正在为我的项目创建这个电影测验应用程序，我很难找出它的查询。如果你能帮助我，我将不胜感激。

所以，架构如下所示。表1：电影值 - id（主键）标题，年份，导演，电影

表2：明星 values - id（主键）first_name，last_name

表3：stars_in_movie 值 - star_id，movie_id

以下是我需要查询的问题。

Who directed the movie X? I figuered this one out.

从stars_in_movies内连接星中选择first_name，last_name，其中movie_id =％s和star_id = id;

Who directed the star X?
Who did not directed the star X?
Which star appears in both movies X and Y?
Which star did not appear in the same movie with the star X?
Who directed the star X in year Y?

感谢您的帮助。谢谢。

Answer 1

虽然您可能需要处理mysql语法，但这里有一些广泛的提示。您可以使用mysql语法而不是IN来使用内部联接来更有效地完成此操作。

select director from movies where movieid in (select movieid from star_in_movie where starid in (select starid from stars where first_name like ....  ))

select director from movies where movieid NOT in (select movieid from star_in_movie where starid in (select starid from stars where first_name like ....  ))

select first_name, last_name from stars where (starid in (select starid from star_in_movie where movieid in (select movieid from movies where title = X)))
And 
(starid in (select starid from star_in_movie where movieid in (select movieid from movies where title = X)))

我会根据上面的提示将其他两个留给你的想象力。如果您仍然需要帮助，请告诉我。 mysql中内连接的语法必须类似于：X.colname = Y.colname上的X内连接Y.

数据库查询

1 个答案: