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Development Tools Database Foundations SQL Calculating, Aggregating and Other Functions Grouping, Joining and Cleaning Up

Posted by Jacinda Zhong
Jacinda Zhong
3,695 Points

MySQL join code issues

I am working on a MySQL code challenge, and am a little stuck...

Question: Like before, select the average "score" as "average", setting to 0 if null, by grouping the "movie_id" from the "reviews" table. Also, do an outer join on the "movies" table with its "id" column and display the movie "title" before the "average". Finally, filter out any "average" score over 2.

Code: (that's not working) SELECT IFNULL(AVG(score), 0) AS average FROM reviews OUTER JOIN movies ON movies.id = title, average GROUP BY movie_id HAVING average <= 2;

Help! There's something weird with my join, but I'm not sure why...

1 Answer

bothxp
bothxp
16,510 Points

My answer was:

SELECT title, ifnull(avg(score),0) as average 
FROM movies left outer join reviews 
ON movies.id = reviews.movie_id 
GROUP BY movie_id 
HAVING average <= 2;
Jacinda Zhong
Jacinda Zhong
3,695 Points

Ah, I see. I was trying to join the movies table to the reviews table, instead of the other way around. Thanks bothxp!