如何连接两个具有不相关列的表 SQL

Question

I am trying to join two tables together using UNION (although im not sure that is the best option) there are technically two related columns however they don't have the same name so i'm assuming that isn't an option here is my query:

SELECT title, type, release_date FROM pictures
UNION
SELECT name, residence, NULL as Col3 FROM actor
ORDER BY release_date ASC;

It is only printing out the pictures columns from this? Thank you for any help in advance.

Answer 1

To relate two tables you could use some foreign key or a third table in the case of beign a many-to-many relation, you should use one of the join options, for example:

• Imagine that exists a table that relate actor and pictures, called actor_pictures.
• Image that we will relate the tables by id (it could be another one, and it doesn't have to have the same name).

You could do this:

SELECT * FROM actor_pictures ap 
JOIN actor a ON ap.actor_id = a.id 
JOIN pictures p ON ap.pictures_id = p.id
ORDER BY p.release_date ASC

Read this: https://www.w3schools.com/sql/sql_join.asp