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SQL exercises on movie Database: Find the first and last name of all the directors with number of genres movies they directed with genres name, and arranged the result alphabetically with the first and last name of the director

SQL movie Database: Join Exercise-6 with Solution

6. From the following table, write a SQL query to find the directors who have directed films in a variety of genres. Group the result set on director first name, last name and generic title. Sort the result-set in ascending order by director first name and last name. Return director first name, last name and number of genres movies.

Sample table: director
 dir_id |      dir_fname       |      dir_lname
--------+----------------------+----------------------
    201 | Alfred               | Hitchcock
    202 | Jack                 | Clayton
    203 | David                | Lean
    204 | Michael              | Cimino
    205 | Milos                | Forman
    206 | Ridley               | Scott
    207 | Stanley              | Kubrick
    208 | Bryan                | Singer
    209 | Roman                | Polanski
    210 | Paul                 | Thomas Anderson
    211 | Woody                | Allen
    212 | Hayao                | Miyazaki
    213 | Frank                | Darabont
    214 | Sam                  | Mendes
    215 | James                | Cameron
    216 | Gus                  | Van Sant
    217 | John                 | Boorman
    218 | Danny                | Boyle
    219 | Christopher          | Nolan
    220 | Richard              | Kelly
    221 | Kevin                | Spacey
    222 | Andrei               | Tarkovsky
    223 | Peter                | Jackson
Sample table: movie_direction
 dir_id | mov_id
--------+--------
    201 |    901
    202 |    902
    203 |    903
    204 |    904
    205 |    905
    206 |    906
    207 |    907
    208 |    908
    209 |    909
    210 |    910
    211 |    911
    212 |    912
    213 |    913
    214 |    914
    215 |    915
    216 |    916
    217 |    917
    218 |    918
    219 |    919
    220 |    920
    218 |    921
    215 |    922
    221 |    923

Sample table: genres
 gen_id |      gen_title
--------+----------------------
   1001 | Action
   1002 | Adventure
   1003 | Animation
   1004 | Biography
   1005 | Comedy
   1006 | Crime
   1007 | Drama
   1008 | Horror
   1009 | Music
   1010 | Mystery
   1011 | Romance
   1012 | Thriller
   1013 | War

Sample table: movie_genres

 mov_id | gen_id
--------+--------
    922 |   1001
    917 |   1002
    903 |   1002
    912 |   1003
    911 |   1005
    908 |   1006
    913 |   1006
    926 |   1007
    928 |   1007
    918 |   1007
    921 |   1007
    902 |   1008
    923 |   1009
    907 |   1010
    927 |   1010
    901 |   1010
    914 |   1011
    906 |   1012
    904 |   1013

Sample Solution:

-- Selecting director first names, last names, genre titles, and the count of genre titles
-- Using the 'director' table
SELECT dir_fname, dir_lname, gen_title, COUNT(gen_title)
FROM director
-- Joining with 'movie_direction' using NATURAL JOIN to link directors with movies
NATURAL JOIN movie_direction
-- Further joining with 'movie_genres' using NATURAL JOIN to get additional movie genres information
NATURAL JOIN movie_genres
-- Joining with 'genres' using NATURAL JOIN to retrieve genre titles
NATURAL JOIN genres
-- Grouping the result by director names and genre titles
GROUP BY dir_fname, dir_lname, gen_title
-- Ordering the result by director first names and last names
ORDER BY dir_fname, dir_lname;

Sample Output:

      dir_fname       |      dir_lname       |      gen_title       | count
----------------------+----------------------+----------------------+-------
 Alfred               | Hitchcock            | Mystery              |    1
 Bryan                | Singer               | Crime                |    1
 Danny                | Boyle                | Drama                |    2
 David                | Lean                 | Adventure            |    1
 Frank                | Darabont             | Crime                |    1
 Hayao                | Miyazaki             | Animation            |    1
 Jack                 | Clayton              | Horror               |    1
 James                | Cameron              | Action               |    1
 John                 | Boorman              | Adventure            |    1
 Kevin                | Spacey               | Music                |    1
 Michael              | Cimino               | War                  |    1
 Ridley               | Scott                | Thriller             |    1
 Sam                  | Mendes               | Romance              |    1
 Stanley              | Kubrick              | Mystery              |    1
 Woody                | Allen                | Comedy               |    1
(15 rows)

Code Explanation:

The said query in SQL that joins the tables director, movie_direction, movie_genres, and genres, and retrieves the first name and last name of the directors, the genre titles, and the count of movies directed by each director in each genre. The query groups the results by director first name, last name, and genre title, and sorts the results by director first name and last name.
The NATURAL JOIN keyword, which joins tables based on columns with the same name in each table. This joins the director table with the movie_direction table to get the movies directed by each director. Then joins the resulting table with the movie_genres table to get the genre for each movie and then it join the resulting table with the genres table to get the genre title for each genre ID.
The results then grouped by the director first name, last name, and genre title and then it sort the results by director first name and last name.

Alternative Solutions:

Using INNER JOIN and GROUP BY:

SELECT a.act_fname, a.act_lname, c.mov_title, c.mov_year
SELECT d.dir_fname, d.dir_lname, g.gen_title, COUNT(g.gen_title)
FROM director d
JOIN movie_direction md ON d.dir_id = md.dir_id
JOIN movie_genres mg ON md.mov_id = mg.mov_id
JOIN genres g ON mg.gen_id = g.gen_id
GROUP BY d.dir_fname, d.dir_lname, g.gen_title
ORDER BY d.dir_fname, d.dir_lname;

Explanation:

This query uses INNER JOINs to combine the director, movie_direction, movie_genres, and genres tables based on their respective IDs. It then applies a GROUP BY clause to group the results by director names (dir_fname, dir_lname) and genre titles (gen_title), along with a COUNT to get the count of each genre. The results are ordered by director names.

Using WHERE Clause with Table Aliases and GROUP BY:

SELECT a.act_fname, a.act_lname, c.mov_title, c.mov_year
SELECT d.dir_fname, d.dir_lname, g.gen_title, COUNT(g.gen_title)
FROM director d, movie_direction md, movie_genres mg, genres g
WHERE d.dir_id = md.dir_id
  AND md.mov_id = mg.mov_id
  AND mg.gen_id = g.gen_id
GROUP BY d.dir_fname, d.dir_lname, g.gen_title
ORDER BY d.dir_fname, d.dir_lname;

Explanation:

This query uses the older comma-separated syntax for joining tables and specifies the join conditions in the WHERE clause. It then applies a GROUP BY clause to group the results by director names and genre titles, along with a COUNT to get the count of each genre. The results are ordered by director names.

Relational Algebra Expression:

Relational Algebra Expression: Find the first and last name of all the directors with number of genres movies they directed with genres name, and arranged the result alphabetically with the first and last name of the director.

Relational Algebra Tree:

Relational Algebra Tree: Find the first and last name of all the directors with number of genres movies they directed with genres name, and arranged the result alphabetically with the first and last name of the director.

Practice Online


Movie database model

Query Visualization:

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Previous: From the following tables, write a SQL query to find the actors who have not acted in any movie between1990 and 2000 (Begin and end values are included.). Return actor first name, last name, movie title and release year.
Next: From the following table, write a SQL query to find the movies with year and genres. Return movie title, movie year and generic title.

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