sqlzoo练习12-more-join

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发布于 2021-03-01 11:03:16

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文章被收录于专栏：机器学习/数据可视化机器学习/数据可视化

sqlzoo练习12-More Join

This tutorial introduces the notion of a join. The database consists of three tablemovie, actorand casting .

more-join

练习-基础

List the films where the yr is 1962 [Show id, title]

select id, title
from movie
where yr=1962;

Give year of ‘Citizen Kane’.

select yr
from movie
where title='Citizen Kane';

List all of the Star Trek movies, include the id, title and yr (all of these movies include the words Star Trek in the title). Order results by year.

select id, title, yr
from movie
where title like '%Star Trek%'
order by yr;

What id number does the actor ‘Glenn Close’ have?

select id
from actor
where name='Glenn Close';

What is the id of the film ‘Casablanca’

select id
from movie
where title='Casablenca';

Obtain the cast list for ‘Casablanca’.

Use movieid=11768, (or whatever value you got from the previous question)

What is a cast list The cast list is the names of the actors who were in the movie. 将某个电影中的全部演员列出来

select name
from actor
join casting on actor.id=casting.actorid
where movieid=11768;

Obtain the cast list for the film ‘Alien’

Alien这个演员的cast list

select name
from actor
join casting on actor.id=casting.actorid
where movieid = (select movie.id
                 from movie
                 where title='Alien');

List the films in which ‘Harrison Ford’ has appeared

笔记：列出这个演员出现的所有电影。 movie 和actor两个表是没有直接联系的，只能通过casting表的actorid字段来进行搭桥

select title
from movie
join casting on movie.id = casting.movieid
where actorid = (select id
                 from actor
                 where name='Harrison Frod');

List the films where ‘Harrison Ford’ has appeared - but not in the starring role. [Note: the ord field of casting gives the position of the actor. If ord=1 then this actor is in the starring role]

列出该演员出现但不是主演（ord=1）的电影

select title
from movie
join casting on movie.id=casting.movieid
where actorid = (select id
                 from actor
                 where name='Harrison Ford')
and ord != 1;

List the films together with the leading star for all 1962 films.

笔记：列出1962年的所有电影和主演名字

主演：ord-casting表
演员名字：name-actor表

select title, name
from movie
join casting on movie.id=casting.movieid
join actor on actor.id=casting.actorid
where yr=1962
and casting.ord = 1;

Which were the busiest years for ‘Rock Hudson’, show the year and the number of movies he made each year for any year in which he made more than 2 movies.

找出该演员的电影数目大于2的年份

演员name
年份yr
电影movie

select yr, count(title)   -- 统计电影数目
from movie
join casting on movie.id = movieid  -- 联结顺序：movie---> casting---> actor
join actor on actorid = actor.id
where name = 'Rock Hudson'    -- 通过两个连接将movie 和 actor表进行联结
group by yr
having count(title) > 2;

List the film title and the leading actor for all of the films ‘Julie Andrews’ played in.

找出JA演员参加的电影和主演

select title, name   -- 找出电影和主演
from movie
join casting on (movieid=movie.id and ord=1)   -- 3. 找出主演
join actor on (actorid=actor.id)
where movie.id in (select movieid    -- 2.从1中选择出的全部演员中找出全部的电影movieid
                  from casting
                  where actorid in (select id   -- 1. 找出JA参加的电影的全部演员actorid
                                  from actor
                                  where name='Julie Andrews'))

解题步骤

先找出JA参加的电影的全部演员actroid
找出上步中的演员参演的电影movieid
确定主演ord=1
找出电影和主演

Obtain a list, in alphabetical order, of actors who’ve had at least 15 starring roles.

找出至少当过15次主角（ord，casting表）的演员名字name(actor) 按照名字的字母排序

select name
from actor
join casting on casting.actorid=actor.id
group by name
having sum(case ord when 1 then 1 else 0 end) >= 15  -- 当ord=1则计数1，sum求和
order by name;

List the films released in the year 1978 ordered by the number of actors in the cast, then by title.

1978年发行的电影
根据电影中的演员数量进行排名
再根据title排名

select title, count(*) as actorcount
from movie
join casting on movie.id = casting.movieid
where yr=1978
group by title
order by actorcount desc, title

List all the people who have worked with ‘Art Garfunkel’.

找出和AG合作的全部演员

select name
from actor join casting
on casting.actorid=actor.id
where movieid in (select movieid     -- 2. 筛选合作演员的电影
                  from casting
                  where actorid= (select id  -- 1. 筛选和AG合作的演员id
                                  FROM actor
                                  WHERE name='Art Garfunkel'))
and name != 'Art Garfunkel';