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Databases

Brendan Whiting
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Brendan Whiting
Front End Web Development Techdegree Graduate 84,704 Points

What's wrong with my SQL query?

This is the challenge - Challenge Task 3 of 3:

https://teamtreehouse.com/library/database-foundations/sql-calculating-aggregating-and-other-functions/grouping-joining-and-cleaning-up-2

This is what they're asking me to do:

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, include averages under 2.

This is my attempt:

SELECT movies.title, IFNULL(AVG(score),0) AS average FROM reviews LEFT OUTER JOIN movies ON reviews.movie_id = movies.id GROUP BY movie_id HAVING average < 2;

1 Answer

Thomas Nilsen
Thomas Nilsen
14,957 Points

try this:

select 
m.title, 
AVG(IFNULL(r.score, 0)) as average 
from reviews r 

right outer join movies m on m.id = r.movie_id 

group by r.movie_id 
having AVG(IFNULL(r.score, 0)) < 2