Difference between revisions of "More JOIN operations"

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{{Languages|More_JOIN_operations}}
 
<p>This tutorial introduces the notion of a join. The database
 
<p>This tutorial introduces the notion of a join. The database
 
consists of three tables  
 
consists of three tables  
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   .
 
   .
 
</p>
 
</p>
<div class='sc'></div>
 
<div class = 'ref_section'>
 
<table class = 'db_ref'>
 
<tr><th>'''movie'''</th><th>'''actor'''</th><th>'''casting'''</th></tr>
 
<tr><td><u title='primary key'>id</u></td><td><u title='primary key'>id</u></td><td><u title='primary key and foreign key'><i>movieid</i></u></td></tr>
 
<tr><td>title</td><td>name</td><td><u title='primary key and foreign key'><i>actorid</i></u></td></tr>
 
<tr><td>yr</td><td></td><td><u>ord</u></td></tr>
 
<tr><td>director</td><td></td><td></td></tr>
 
<tr><td>budget</td><td></td><td></td></tr>
 
<tr><td>gross</td><td></td><td></td></tr>
 
<tr><td></td><td></td><td></td></tr>
 
</table>
 
  
<table><caption>movie</caption>
+
<table style='display:inline-block;margin:2ex;'><caption>movie</caption>
 
<tr>
 
<tr>
 
<td><b>id</b></td>
 
<td><b>id</b></td>
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</table>
 
</table>
  
<table><caption>actor</caption>
+
<table style='display:inline-block;margin:2ex;'><caption>actor</caption>
 
<tr>
 
<tr>
 
<td><b>id</b></td>
 
<td><b>id</b></td>
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</table>
 
</table>
  
<table><caption>casting</caption>
+
<table style='display:inline-block;margin:2ex;'><caption>casting</caption>
 
<tr>
 
<tr>
 
<td><b><i>movieid</i></b></td>
 
<td><b><i>movieid</i></b></td>
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</table>
 
</table>
  
[[File:movie-er.png]]
+
[[File:movie2-er.png]]
 
</div>
 
</div>
 
   <p>
 
   <p>
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<hr>
 
<hr>
  
==Busy years for John Travolta==
+
==Busy years for Rock Hudson==
 
<div class='qu'>
 
<div class='qu'>
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.       
+
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.       
 
<source lang='sql' class='def'>
 
<source lang='sql' class='def'>
 
SELECT yr,COUNT(title) FROM
 
SELECT yr,COUNT(title) FROM
 
   movie JOIN casting ON movie.id=movieid
 
   movie JOIN casting ON movie.id=movieid
        JOIN actor  ON actorid=actor.id
+
        JOIN actor  ON actorid=actor.id
where name='John Travolta'
+
WHERE name='Doris Day'
 
GROUP BY yr
 
GROUP BY yr
HAVING COUNT(title)=(SELECT MAX(c) FROM
+
HAVING COUNT(title) > 1
(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
 
)
 
 
</source>
 
</source>
  
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SELECT yr,COUNT(title) FROM
 
SELECT yr,COUNT(title) FROM
 
   movie JOIN casting ON movie.id=movieid
 
   movie JOIN casting ON movie.id=movieid
        JOIN actor  ON actorid=actor.id
+
        JOIN actor  ON actorid=actor.id
where name='John Travolta'
+
where name='Rock Hudson'
 
GROUP BY yr
 
GROUP BY yr
HAVING COUNT(title)=(SELECT MAX(c) FROM
+
HAVING COUNT(title) > 2
(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
 
)
 
 
</source>
 
</source>
 
</div>
 
</div>
 +
 
==Lead actor in Julie Andrews movies==
 
==Lead actor in Julie Andrews movies==
 
<div class='qu'>
 
<div class='qu'>
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</div>
 
</div>
  
==Actors with 30 leading roles==
+
==Actors with 15 leading roles==
 
<div class='qu'>
 
<div class='qu'>
Obtain a list, in alphabetical order, of actors who've had at least 30 starring roles.         
+
Obtain a list, in alphabetical order, of actors who've had at least 15 '''starring''' roles.         
 
<source lang='sql' class='def'>
 
<source lang='sql' class='def'>
 
</source>
 
</source>
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     WHERE ord=1
 
     WHERE ord=1
 
     GROUP BY name
 
     GROUP BY name
     HAVING COUNT(movieid)>=30
+
     HAVING COUNT(movieid)>=15
 
</source>
 
</source>
 
</div>
 
</div>

Latest revision as of 11:47, 24 March 2020

Language:Project:Language policy English  • 日本語 • 中文

This tutorial introduces the notion of a join. The database consists of three tables movie , actor and casting .

movie
id title yr director budget gross
actor
id name
casting
movieid actorid ord

Movie2-er.png

More details about the database.


Summary

1962 movies

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

SELECT id, title
 FROM movie
 WHERE yr=1962
SELECT id, title
 FROM movie
 WHERE yr=1962

When was Citizen Kane released?

Give year of 'Citizen Kane'.

SELECT yr 
FROM movie 
WHERE title='Citizen Kane'

Star Trek movies

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

id for actor Glenn Close

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

SELECT id FROM actor
  WHERE name= 'Glenn Close'


id for Casablanca

What is the id of the film 'Casablanca'

SELECT id 
FROM movie 
WHERE title='Casablanca'

Get to the point

Cast list for Casablanca

Obtain the cast list for 'Casablanca'.

The cast list is the names of the actors who were in the movie.

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

SELECT name
  FROM casting, actor
  WHERE movieid=(SELECT id 
             FROM movie 
             WHERE title='Casablanca')
    AND actorid=actor.id

Alien cast list

Obtain the cast list for the film 'Alien'

SELECT name
  FROM movie, casting, actor
  WHERE title='Alien'
    AND movieid=movie.id
    AND actorid=actor.id

Harrison Ford movies

List the films in which 'Harrison Ford' has appeared

SELECT title
  FROM movie, casting, actor
 WHERE name='Harrison Ford'
    AND movieid=movie.id
    AND actorid=actor.id

Harrison Ford as a supporting actor

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, casting, actor
 WHERE name='Harrison Ford'
    AND movieid=movie.id
    AND actorid=actor.id
  AND ord<>1

Lead actors in 1962 movies

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

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

Harder Questions


Busy years for Rock Hudson

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.

SELECT yr,COUNT(title) FROM
  movie JOIN casting ON movie.id=movieid
        JOIN actor   ON actorid=actor.id
WHERE name='Doris Day'
GROUP BY yr
HAVING COUNT(title) > 1
SELECT yr,COUNT(title) FROM
  movie JOIN casting ON movie.id=movieid
        JOIN actor   ON actorid=actor.id
where name='Rock Hudson'
GROUP BY yr
HAVING COUNT(title) > 2

Lead actor in Julie Andrews movies

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

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

Actors with 15 leading roles

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

SELECT name
    FROM casting JOIN actor
      ON  actorid = actor.id
    WHERE ord=1
    GROUP BY name
    HAVING COUNT(movieid)>=15

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 casting,movie                
  WHERE yr=1978
        AND movieid=movie.id
  GROUP BY title
  ORDER BY 2 DESC,1 ASC

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

SELECT DISTINCT d.name
FROM actor d JOIN casting a ON (a.actorid=d.id)
   JOIN casting b on (a.movieid=b.movieid)
   JOIN actor c on (b.actorid=c.id 
                and c.name='Art Garfunkel')
  WHERE d.id!=c.id
Clear your results

That is definitely enough. Students should, under no circumstances look at the next tutorial, concerning outer joins.