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Databases

drstrangequark
drstrangequark
8,273 Points
Posted by drstrangequark
drstrangequark
8,273 Points

I thought you couldn't use a WHERE clause when using the SUM keyword?

The challenge is:

We're in a movie database. There's a reviews table with the columns of id, movie_id, username, review and rating. The movie "Starman" has the id of 6. Movie ids are found in the movie_id column in the reviews table. Write a query that totals up all ratings for the movie "Starman" in the reviews table. Alias it as starman_total_ratings.

My query:

SELECT SUM(review) AS "starman_total_ratings" FROM reviews GROUP BY movie_id HAVING movie_id = 6;

I get the error: You're missing the WHERE clause. However I thought that you COULDN'T use a WHERE clause with a SUM keyword and that was the whole point of using the HAVING keyword. Plus, when I try to replace the HAVING keyword with WHERE, it also returns an error.

4 Answers

markmneimneh
markmneimneh
14,132 Points

Hello

Try this. If you want to use Where, the Where clause needs to come before group by.

SELECT SUM(review) AS "starman_total_ratings" 
FROM 
reviews 
WHERE movie_id = 6
GROUP BY movie_id;

Hope this answers this question

drstrangequark
drstrangequark
8,273 Points
drstrangequark
drstrangequark
8,273 Points

Thanks for the response. When I tried your query I got back "Your query didn't perform the correct sum calculation."

Paul Leenheer
PLUS
Paul Leenheer
Courses Plus Student 11,720 Points
Paul Leenheer
Paul Leenheer
Courses Plus Student 11,720 Points

Hi guys,

The correct code is the following:

SELECT SUM(rating) AS "starman_total_ratings" FROM reviews WHERE movie_id = 6 GROUP BY movie_id;

It was one little mistake. Only the review must be replaced by rating.

Greetings,

Dylan

drstrangequark
drstrangequark
8,273 Points
drstrangequark
drstrangequark
8,273 Points

Nevermind. I'm an idiot. I was getting the sum of Review when I should have been getting the sum of Rating

markmneimneh
markmneimneh
14,132 Points

Hello

I do same type of mistakes all the time. Glad you got it resolved.