I have to run a query from SQL. Perhaps too easy or not, but unfortunately I do not understand SQL. So here's my tables:
films
id | movie_name
------------
1 | prometheus
names
id | person_name
-----------------
1 | Ridley Scott
2 | Noomi Rapace
3 | Michael Fassbender
4 | Charlize Theron
5 | Damon Lindelof
films_cast
id | film_id | person_id | type
-------------------------------
1 | 1 | 1 | director
2 | 1 | 2 | actor
3 | 1 | 3 | actor
4 | 1 | 4 | actor
5 | 1 | 5 | writer
And how can I reach such a conclusion from these tables:
film_archive
id | movie_name | director | writer | cast
---------------------------------------------------------------------------------------
1 | prometheus | Ridley Scott | Damon Lindelof | Noomi Rapace, Michael Fassbender, Charlize Theron
Thank you!
You need to join your tables, then group by film performing GROUP_CONCAT()
aggregation on the names column given a suitable condition:
SELECT f.id,
f.movie_name,
GROUP_CONCAT(IF(c.type='director', n.person_name, NULL)) AS director,
GROUP_CONCAT(IF(c.type='writer', n.person_name, NULL)) AS writer,
GROUP_CONCAT(IF(c.type='actor', n.person_name, NULL)) AS cast
FROM films f LEFT JOIN films_cast c ON c.film_id = f.id
LEFT JOIN names n ON c.person_id = n.id
GROUP BY f.id
See it on sqlfiddle .
Since you also have the sql-server
tag on your question, unfortunately sql-server doesn't have GROUP_CONCAT
, an alternative like FOR XML / STUFF is needed:
SELECT f.id, f.movie_name,
STUFF((SELECT ',' + p.person_name
FROM persons p
INNER JOIN films_cast fc on fc.person_id = p.id
WHERE fc.film_id = f.id AND fc.type = 'director'
FOR XML PATH (''))
, 1, 1, '') AS director,
STUFF((SELECT ',' + p.person_name
FROM persons p
INNER JOIN films_cast fc on fc.person_id = p.id
WHERE fc.film_id = f.id AND fc.type = 'writer'
FOR XML PATH (''))
, 1, 1, '') AS writer,
STUFF((SELECT ',' + p.person_name
FROM persons p
INNER JOIN films_cast fc on fc.person_id = p.id
WHERE fc.film_id = f.id AND fc.type = 'actor'
FOR XML PATH (''))
, 1, 1, '') AS cast
FROM films f;
Try this,
SELECT a.id, a.movie_name,
GROUP_CONCAT((CASE WHEN b.type = 'director' THEN c.person_name ELSE NULL END)) as `director`,
GROUP_CONCAT((CASE WHEN b.type = 'writer' THEN c.person_name ELSE NULL END)) as `writer`,
GROUP_CONCAT((CASE WHEN b.type = 'actor' THEN c.person_name ELSE NULL END)) as `cast`
FROM films a
LEFT JOIN film_cast b
ON a.id = b.film_id
LEFT JOIN names c
ON b.person_id = c.id
GROUP BY a.id, a.movie_name
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