Question

I have two tables, one called episodes, and one called score. The episode table has the following columns:

id | number | title | description | type

The score table has the following columns:

id | userId | showId | score

The idea is that users will rate a show. Each time a user rates a show, a new row is created in the score table (or updated if it exists already). When I list the shows, I average all the scores for that show ID and display it next to the show name.

What I need to be able to do is sort the shows based on their average rating. I’ve looked at joining the tables, but haven’t really figured it out.

Thanks

Answer 1

To order the results, use and ORDER BY clause. You can order by generated columns, such as the result of an aggregate function like AVG.

SELECT e.title, AVG(s.score) AS avg_score
  FROM episodes AS e
    LEFT JOIN scores AS s ON e.id=s.showId
  GROUP BY e.id
  ORDER BY avg_score DESC;