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Databases Reporting with SQL Aggregate and Numeric Functions Counting Groups

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

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