How to get average with orderBy Desc in Laravel 5

Question

I have 2 tables in my database.

books and ratings

in books id, name

in ratings

Answer 1

That query would look something like this:

SELECT book.id, AVG(ratings.rating) AS avg_rating 
FROM ratings
JOIN book ON book.id = ratings.book_id
/* WHERE AVG(ratings.rating) > 4 You could say only return results where rating > 4 */
GROUP BY book.id
ORDER BY AVG(ratings.rating) DESC LIMIT 5;

You need to join the two tables, use an aggregate function with a group by on the book. Then just sort and limit the results.

UPDATE:

In response to your question:

SELECT book.id, COALESCE(AVG(ratings.rating), 0) AS avg_rating 
FROM book
*LEFT* JOIN ratings ON book.id = ratings.book_id    
GROUP BY book.id
ORDER BY AVG(ratings.rating);

Use of a view might be something of a compromise between ease of the ORM and sanity in your querying.