Question

I have a problem with a mysql join i’m trying to complete.
This is my code:

SELECT title, books.`author_id`, books.`publisher_id`, books.`format_id`, books.`genre_id`, pages, isbn, description, DATE_FORMAT(release_date, '%M, %d, %Y') 
FROM `books`
INNER JOIN `authors` ON (`authors`.`author_id`= `books`.`author_id`)
INNER JOIN `publishers` ON (`publishers`.`publisher_id`= `books`.`publisher_id`)
INNER JOIN `formats` ON (`formats`.`format_id`= `books`.`format_id`)
INNER JOIN `genres` ON (`genres`.`genre_id`= `books`.`genre_id`)`

authors, publishers, formats and genres are all separate tables each with two columns. author_id and author in the case of the authors table, and the same format for the others.

The join doesn’t seem to work no matter what i do, please help me to see where i’ve gone wrong.

Answer 1

The problem is in the select part of your query.

SELECT title, books.`author_id`, books.`publisher_id`, books.`format_id`, books.`genre_id`

You are selecting the author_id, publisher_id, format_id and genre_id from the books table, and nothing from the joined tables, so it is no wonder that you are missing the values you want.

SELECT title, books.`author_id`, authors.`author`, books.`publisher_id`, publishers.`publisher`, books.`format_id`, formats.`format`, books.`genre_id`, genres.`genre`

This will produce the values you want in addition to the id values.