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Databases

Alan Ayoub
Alan Ayoub
40,294 Points
Posted by Alan Ayoub
Alan Ayoub
40,294 Points

Reporting with SQL....

I'm totally stuck here, I feel like the DISTINCT explanation was like 3 seconds? I have no idea what I'm doing wrong!

Challenge Task 2 of 2

In the library database there's a books table. There are id, title, author, genre and first_published columns. Write a query to count all the unique genres in the books table. Alias it as total_genres. Type in your command below.

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

4 Answers

Andrew Winkler
Andrew Winkler
37,739 Points
Andrew Winkler
Andrew Winkler
37,739 Points

Hi there. I agree it was brief, but here's some help. Click here for documentation.

The COUNT(DISTINCT column_name) function returns the number of distinct values of the specified column:

SELECT COUNT (DISTINCT column_name)
FROM table_name;

Spoiler Alert! -- The answer is below.

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SELECT COUNT (DISTINCT genre) 
AS genre_count 
FROM books
GROUP BY genre;
Alan Ayoub
Alan Ayoub
40,294 Points
Alan Ayoub
Alan Ayoub
40,294 Points

Nice! Thanks Andrew!

Charlie Harcourt
Charlie Harcourt
8,046 Points

Andrew I have tried your code and something seems to be going wrong. There doesn't need to be a GROUP BY and the task is asking for total_genres not genre_count. :)

SELECT COUNT (DISTINCT genre) AS total_genres FROM books;

Taylor Henson
Taylor Henson
855 Points

You don't need to add the GROUP BY function

Erik Sorensen
Erik Sorensen
13,846 Points
Erik Sorensen
Erik Sorensen
13,846 Points

This passed:

SELECT COUNT (DISTINCT genre) AS total_genres FROM books;

Aya khaled
PLUS
Aya khaled
Courses Plus Student 1,967 Points
Aya khaled
Aya khaled
Courses Plus Student 1,967 Points

something go wrong with my code SELECT COUNT(DISTINCT genre) AS genre_count FROM books;

Ashton Shingirirai Calton Munkondya
Ashton Shingirirai Calton Munkondya
3,925 Points
Ashton Shingirirai Calton Munkondya
Ashton Shingirirai Calton Munkondya
3,925 Points

SELECT COUNT (DISTINCT genre) AS total_genres FROM books;