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Databases Reporting with SQL Aggregate and Numeric Functions Counting Groups

Posted by newtocoding
newtocoding
4,940 Points

How to answer this challenge?

Hello,

I am trying to answer this question:

In the library database there's a books table. There are id, title, author, genre and first_published columns.

Count all the books in each genre. Include the genre column first and the genre_count as the second column of information.

The code I have written is attached below. I can't figure out what I'm doing wrong so any help will be appreciated!

SELECT genre, COUNT(genre) AS genre_count FROM books GROUP BY genre_count;

2 Answers

KRIS NIKOLAISEN
KRIS NIKOLAISEN
54,971 Points

COUNT(genre) will not include null values. For this use COUNT(*).

You will also want to group by genre since that is what you are counting

Moyosore Banjoko
Moyosore Banjoko
10,204 Points
Moyosore Banjoko
Moyosore Banjoko
10,204 Points

The answer is

SELECT genre, COUNT(*) AS genre_count FROM books GROUP BY genre;

You declare the genre column and when you count you’re counting ALL(*) books in each genre so after you group the count all by genre. Because you want to count all the books but they must be grouped by genre.