SQL Zoo 练习题答案—JOIN & More JOIN

JOIN

1.The first example shows the goal scored by a player with the last name 'Bender'. The *says to list all the columns in the table - a shorter way of saying matchid, teamid, player, gtime

Modify it to show the matchid and player name for all goals scored by Germany. To identify German players, check for: teamid = 'GER'

select matchid, player from goal where teamid = 'GER'

2.From the previous query you can see that Lars Bender's scored a goal in game 1012. Now we want to know what teams were playing in that match.

Notice in the that the column matchid in the goal table corresponds to the id column in the game table. We can look up information about game 1012 by finding that row in the game table.

Show id, stadium, team1, team2 for just game 1012

SELECT id,stadium,team1,team2 FROM game WHERE id= 1012

3.Modify it to show the player, teamid, stadium and mdate and for every German goal.

SELECT player,teamid, stadium, mdate FROM goal JOIN game ON (matchid=id) WHERE teamid = 'GER'

4.Show the team1, team2 and player for every goal scored by a player called Mario player LIKE 'Mario%'

SELECT team1, team2, player FROM game JOIN goal ON id=matchid WHERE player LIKE 'Mario%'

5.Show player, teamid, coach, gtime for all goals scored in the first 10 minutes gtime<=10

SELECT player, teamid, coach, gtime FROM goal join eteam ON teamid = id WHERE gtime<=10

6.List the the dates of the matches and the name of the team in which 'Fernando Santos' was the team1 coach.

SELECT mdate, teamname FROM game JOIN eteam ON team1 = eteam.id WHERE coach = 'Fernando Santos'

7.List the player for every goal scored in a game where the stadium was 'National Stadium, Warsaw'

SELECT player FROM goal JOIN game ON matchid=id WHERE stadium = 'National Stadium, Warsaw'

8.The example query shows all goals scored in the Germany-Greece quarterfinal.

Instead show the name of all players who scored a goal against Germany.

HINT

Select goals scored only by non-German players in matches where GER was the id of either team1 or team2.

You can use teamid!='GER' to prevent listing German players.

You can use DISTINCT to stop players being listed twice.

SELECT DISTINCT player FROM goal JOIN game ON id = matchid WHERE teamid <> 'GER' AND (team1='GER' OR team2='GER')

9.Show teamname and the total number of goals scored.

COUNT and GROUP BY

You should COUNT(*) in the SELECT line and GROUP BY teamname

SELECT teamname, COUNT(teamid) FROM goal JOIN eteam ON teamid=id GROUP BY teamname

10.Show the stadium and the number of goals scored in each stadium.

SELECT stadium, count(gtime) FROM game JOIN goal ON id = matchid GROUP BY stadium

11.For every match involving 'POL', show the matchid, date and the number of goals scored.

SELECT matchid, mdate, COUNT(gtime) FROM game JOIN goal ON matchid = id WHERE (team1 = 'POL' OR team2 = 'POL') GROUP BY matchid, mdate

12.For every match where 'GER' scored, show matchid, match date and the number of goals scored by 'GER'

SELECT id, mdate, COUNT(gtime) FROM game JOIN goal ON id = matchid WHERE (team1 = 'GER' OR team2 = 'GER') AND teamid = 'GER' GROUP BY id, mdate

13.List every match with the goals scored by each team as shown. This will use "CASE WHEN" which has not been explained in any previous exercises.

mdate team1 score1 team2 score2
1 July 2012 ESP 4 ITA 0
10 June 2012 ESP 1 ITA 1
10 June 2012 IRL 1 CRO 3
...

Notice in the query given every goal is listed. If it was a team1 goal then a 1 appears in score1, otherwise there is a 0. You could SUM this column to get a count of the goals scored by team1. Sort your result by mdate, matchid, team1 and team2.

SELECT mdate, team1, SUM(CASE WHEN teamid=team1 THEN 1 ELSE 0 END) AS score1, team2, SUM(CASE WHEN teamid=team2 THEN 1 ELSE 0 END) AS score2 FROM game LEFT JOIN goal ON matchid = id GROUP BY mdate, matchid, team1, team2

More JOIN

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

SELECT id, title FROM movie WHERE yr=1962

2.Give year of 'Citizen Kane'.

SELECT yr FROM movie WHERE title = 'Citizen Kane'

3.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

4.What id number does the actor 'Glenn Close' have?

SELECT id FROM actor WHERE name = 'Glenn Close'

5.What is the id of the film 'Casablanca'

SELECT id FROM movie WHERE title = 'Casablanca'

6.Obtain the cast list for 'Casablanca'.

what is a cast list?

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

SELECT name FROM actor JOIN casting ON id=actorid where movieid = 11768

7.Obtain the cast list for the film 'Alien'

SELECT name FROM actor JOIN casting ON actor.id=actorid where movieid = (select movie.id from movie where title = 'Alien')

8.List the films in which 'Harrison Ford' has appeared

SELECT title FROM movie JOIN casting ON movie.id=movieid WHERE actorid = (SELECT actor.id FROM actor WHERE name = 'Harrison Ford')

9.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]

SELECT title FROM movie JOIN casting ON movie.id=movieid WHERE actorid = (SELECT actor.id FROM actor WHERE name = 'Harrison Ford') AND movieid NOT IN (SELECT movieid FROM actor WHERE ord = 1)

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

SELECT title, name FROM casting JOIN movie ON movie.id=movieid JOIN actor ON actor.id=actorid where ord = 1 AND yr = 1962

11.Which were the busiest years for 'John Travolta', show the year and the number of movies he made each year for any year in which he made more than 2 movies.

SELECT yr,COUNT(title) FROM movie JOIN casting ON movie.id=movieid JOIN actor ON actorid=actor.id where name='John Travolta' GROUP BY yr HAVING COUNT(title)=(SELECT MAX(c) FROM (SELECT yr,COUNT(title) AS c FROM movie JOIN casting ON movie.id=movieid JOIN actor ON actorid=actor.id where name='John Travolta' GROUP BY yr) AS t)

我没太理解这里题干,要求 busiest 同时还有 more than 2 movies.

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

Did you get "Little Miss Marker twice"?

Julie Andrews starred in the 1980 remake of Little Miss Marker and not the original(1934).

Title is not a unique field, create a table of IDs in your subquery

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

这题是要求,列出'Julie Andrews'参与的而不是她是女一号的电影,我的阅读……

13.Obtain a list, in alphabetical order, of actors who've had at least 30 starring roles.

SELECT name FROM actor JOIN casting ON (id=actorid and(select count(ord) FROM casting WHERE actorid = id and ord=1)>=30) GROUP BY name

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

SELECT title, COUNT(actorid) FROM movie JOIN casting ON movie.id=movieid where yr=1978 GROUP BY title ORDER BY COUNT(actorid) DESC, title

这题,题意要搞清楚,因为排序关键词有两个。

15.List all the people who have worked with 'Art Garfunkel'.

SELECT DISTINCT name FROM actor JOIN casting ON actor.id=actorid WHERE movieid IN (SELECT movieid FROM actor JOIN casting ON (actor.id=actorid AND name='Art Garfunkel')) AND name <> 'Art Garfunkel'

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