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Databases Reporting with SQL Aggregate and Numeric Functions Summing Values

Posted by Sonia Cabon
Sonia Cabon
1,173 Points

bummer: you're missing the where cause

with the SUM function and GROUP BY keyword there shouldn't be a WHERE cause but a HAVING cause, right?

3 Answers

Gabriel Plackey
Gabriel Plackey
11,064 Points
Gabriel Plackey
Gabriel Plackey
11,064 Points

I'm not sure where you would be using GROUP BY in this challenge, as you don't need to group anything. Regardless you can use SUM and GROUP BY with the WHERE clause. Like

SELECT SUM(numbers), id, name FROM table WHERE condition GROUP BY name

It can cause errors depending on what is in the table and how it is structured but it is possible. AS for this challenge, the correct answer is

SELECT SUM(rating) AS starman_total_ratings FROM reviews WHERE movie_id = 6;
KRIS NIKOLAISEN
KRIS NIKOLAISEN
54,967 Points
KRIS NIKOLAISEN
KRIS NIKOLAISEN
54,967 Points

You can actually have both in the same SQL statement. WHERE is used to filter records before any groupings take place. HAVING is used to filter values after they have been grouped. Only columns or expression in the group can be included in the HAVING clause’s conditions.

In this case movie_id isn't being grouped. It is being filtered to a specific movie_id.

Sonia Cabon
Sonia Cabon
1,173 Points
Sonia Cabon
Sonia Cabon
1,173 Points

ah great, makes sense! Many thanks :)