Joining two or more tables - sql

Question

I have written some code to merge two tables together. The values that are displayed are null.
+----------+--------------+-----------------------------------------------+-------------+----------+----------+------+----------+
| Movie_ID | Release_year | Movie_Title | Duration | Genre_ID | Actor_ID | Role | Movie_ID |
+----------+--------------+-----------------------------------------------+-------------+----------+----------+------+----------+
| 10001 | 1997 | Titantic | 190 minutes | 40001 | NULL | NULL | NULL |
| 10002 | 1998 | Shakesphere in Love | 123 minutes | 40002 | NULL | NULL | NULL |
| 10003 | 1999 | American Beauty | 122 minutes | 40003 | NULL | NULL | NULL |
| 10004 | 2000 | Gladiator | 155 minutes | 40004 | NULL | NULL | NULL |
| 10005 | 2001 | A beautiful Mind | 135 minutes | 40004 | NULL | NULL | NULL |
| 10006 | 2002 | Chicago | 113 minutes | 40005 | NULL | NULL | NULL |
| 10007 | 2003 | The Lord of the Rings: The return of the King | 201 minutes | 40006 | NULL | NULL | NULL |
| 10008 | 2004 | Million Dollar Baby | 132 minutes | 40007 | NULL | NULL | NULL |
| 10009 | 2005 | Crash | 112 minutes | 40008 | NULL | NULL | NULL |
| 10010 | 2006 | The Departed | 151 minutes | 40009 | NULL | NULL | NULL |
| 10011 | 2007 | No Country for Old Men | 122 minutes | 40009 | NULL | NULL | NULL |
| 10012 | 2008 | Slumdog Millionaire | 120 minutes | 40008 | NULL | NULL | NULL |
| 10013 | 2009 | The Hurt Locker | 131 minutes | 40009 | NULL | NULL | NULL |
| 10014 | 2010 | The King\s speech | 118 minutes | 40010 | NULL | NULL | NULL |
| 10015 | 2011 | The Artist | 100 minutes | 40011 | NULL | NULL | NULL |
| 10016 | 2012 | Argo | 120 minutes | 40012 | NULL | NULL | NULL |
| 10017 | 2013 | 12 Years a Slave | 134 minutes | 40004 | NULL | NULL | NULL |
| 10018 | 2014 | Birdman or The Unexpected Virtue of Ignorance | 119 minutes | 40003 | NULL | NULL | NULL |
| 10019 | 2015 | Spotlight | 129 minutes | 40008 | NULL | NULL | NULL |
| 10020 | 2016 | Moonlight | 111 minutes | 40013 | NULL | NULL | NULL |
| 10021 | 2017 | The Shape of Water | 123 minutes | 40012 | NULL | NULL | NULL |
| 10022 | 2018 | Green Book | 130 minutes | 40011 | NULL | NULL | NULL |
+----------+--------------+-----------------------------------------------+-------------+----------+----------+------+----------+
SELECT *
FROM databaseoscars.movie a
LEFT JOIN databaseoscars.`movie cast` b ON a.Movie_ID = b.Actor_ID;
I expected the output to be all data is displayed on one table.

Answer 1

Your problem is here: a.Movie_ID = b.Actor_ID. A movie will never be an actor. Use your movie cast table's movie ID instead:
SELECT *
FROM databaseoscars.movie m
LEFT JOIN databaseoscars.`movie cast` mc ON mc.movie_id = m.movie_id;
In MySQL and MariaDB, you could also use the USING clause:
SELECT *
FROM databaseoscars.movie m
LEFT JOIN databaseoscars.`movie cast` mc USING (movie_id);