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Databases Reporting with SQL Aggregate and Numeric Functions Counting Groups

Tetiana lukerievas
Tetiana lukerievas
5,641 Points
Posted by Tetiana lukerievas
Tetiana lukerievas
5,641 Points

Is the test outcome correct?

The tests wants me to use COUNT(*), which will count empty categories. But in the task I need "Count all the books in each genre.". No genre is also a gener?

The task: 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.

My solution:

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

1 Answer

ivana kantnerova
ivana kantnerova
15,932 Points
ivana kantnerova
ivana kantnerova
15,932 Points

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

this select first made the groups of genres and after that counts books in the each genre that's mean the (*) is correctly