sql線上練習網站（http://sqlzoo.cn）答案解析（3）

五：How to do joins（http://sqlzoo.cn/3b.htm）
    1a. Show the athelete (who) and the country name for medal winners in 2000
        SELECT who, country.name FROM ttms 
      JOIN country ON (ttms.country=country.id) WHERE games = 2000
    1b. Show the who and the color of the medal for the medal winners from 'Sweden'
        SELECT who, color FROM ttms 
      JOIN country ON (ttms.country=country.id) WHERE country.name = 'Sweden'
    1c. Show the years in which 'China' won a 'gold' medal
        SELECT games FROM ttms JOIN country ON (ttms.country = country.id)
      WHERE name = 'China' AND color = 'gold'
    2a. Show who won medals in the 'Barcelona' games
        SELECT who FROM ttws JOIN games ON (ttws.games=games.yr) WHERE city = 'Barcelona'
    2b. Show which city 'Jing Chen' won medals. Show the city and the medal color
        SELECT city,color FROM games JOIN ttws ON( ttws.games=games.yr) WHERE who = 'Jing Chen'
    2c. Show who won the gold medal and the city
        SELECT who, city FROM ttws JOIN games ON(ttws.games = games.yr) WHERE color = 'gold'
    3a. Show the games and color of the medal won by the team that includes 'Sen Yan'
        SELECT games,color FROM ttmd JOIN team ON(ttmd.team = team.id) WHERE team.name = 'Sen Yan'
    3b. Show the 'gold' medal winners in 2004
        SELECT name FROM team JOIN ttmd ON(ttmd.team = team.id) WHERE color = 'gold' AND games = 2004
    3c. Show the name of each medal winner country 'FRA'
        SELECT name FROM team JOIN ttmd ON(ttmd.team = team.id) WHERE country = 'FRA'

六：The JOIN operation（http://sqlzoo.cn/3.htm）
    1a. 列出獲得不少於30000 votes（選票）的電影． [顯示 title, votes] 
        SELECT title, votes FROM movie WHERE votes>=30000
    1b. 電影'Citizen Kane'的首映年份
        SELECT yr FROM movie WHERE title = 'Citizen Kane'
    1c. 列出包含the Police Academy（警校）字樣的title（電影名稱）和 score（得分） films. [The films have a title that is LIKE 'Police Academy%'] 
        SELECT title,score FROM movie Where title LIKE 'Police Academy%'
    1d. 列出所有the Star Trek movies（星際系列電影）,顯示title（電影標題）和score（得分）. 按電影的發行 yr（年份）排序
        SELECT title,score FROM movie WHERE title LIKE '%Star Trek%' ORDER BY yr ASC
    1e. 列出名稱中包含'Dog'的電影名和得分
        SELECT title,score FROM movie WHERE title LIKE '%Dog%'
    2a. 列出id為 1, 2, 3的電影的名稱
        SELECT title FROM movie WHERE id in (1,2,3)
    2b. 電影'Glenn Close' 的ID號是多少? 
        SELECT id FROM actor WHERE name= 'Glenn Close'
    2c. 電影'Casablanca' 的ID號是多少? 
        SELECT id FROM movie WHERE title = 'Casablanca'
    3a. 顯示id=1的電影'Star Wars'（星球大戰）中演員（角色）名單
        SELECT name FROM casting, actor WHERE movieid=1 AND actorid=actor.id
    or:  SELECT name FROM movie, casting, actor WHERE movie.title = 'Star Wars' AND movie.id = casting.movieid AND casting.actorid = actor.id
    3b. 顯示電影'Alien'的演員（角色）名單
        SELECT name FROM actor, casting, movie
WHERE movie.title = 'Alien' AND movie.id = casting.movieid AND casting.actorid = actor.id
    3c. 顯示有'Harrison Ford'參演的電影名稱
        SELECT title FROM movie 
      JOIN actor ON actor.name = 'Harrison Ford' 
      JOIN casting ON movie.id = casting.movieid AND casting.actorid = actor.id 
    3d. 顯示有'Harrison Ford'參演的電影名稱，但'Harrison Ford'在該影片中不是主角（即在角色表中不是排名第一）
        SELECT title FROM movie 
      JOIN actor ON actor.name = 'Harrison Ford' 
      JOIN casting ON movie.id = casting.movieid AND casting.actorid = actor.id AND casting.ord != 1
    3e. 顯示1962年發行的電影以及該影片中主角（即在角色表中排名第一）
        SELECT title,name FROM actor 
      JOIN movie ON movie.yr = 1962 
      JOIN casting ON movie.id = casting.movieid AND casting.actorid = actor.id AND casting.ord = 1
    4a. 'John Travolta'哪一年最忙？ 顯示出他每年的出演電影數量
        SELECT yr,COUNT(title) FROM movie 
      JOIN actor ON actor.name = 'John Travolta' 
      JOIN casting ON movie.id = casting.movieid AND casting.actorid = actor.id 
      GROUP BY yr
    4b. 列出有'Julie Andrews'參演的所有電影名稱以及該片的主角
        SELECT title, name FROM movie, casting, actor WHERE casting.movieid = movie.id AND casting.actorid = actor.id AND casting.ord = 1 AND casting.movieid IN (SELECT movieid FROM casting, actor WHERE casting.actorid = actor.id AND actor.name = 'Julie Andrews')
    4c. 列出那些最起碼在10部電影中出任過主角的演員
        SELECT name FROM casting 
      JOIN actor ON  casting.actorid = actor.id WHERE casting.ord=1
      GROUP BY name HAVING COUNT(movieid)>=10
    or:  SELECT name FROM actor,casting,movie 
        WHERE casting.actorid = actor.id AND casting.ord = 1 AND movie.id = casting.movieid 
        GROUP BY name HAVING COUNT(casting.movieid)>=10
    4d. 按演員人數的多少依次列出1978 的電影以及演員數．人數最多排在最前
        SELECT title,count(actorid) FROM movie, casting WHERE casting.movieid = movie.id AND movie.yr = 1978
      GROUP BY title ORDER BY 2 DESC
    4e. 列出所有和'Art Garfunkel'合作過的演員（不要列出'Art Garfunkel'他自己）
        SELECT DISTINCT name FROM actor,casting WHERE actor.id = casting.actorid 
      AND casting.movieid IN (SELECT movieid FROM casting,actor 
        WHERE casting.actorid = actor.id AND actor.name = 'Art Garfunkel')
      AND name != 'Art Garfunkel'

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