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Databases

qianyi wang
qianyi wang
601 Points
Posted by qianyi wang
qianyi wang
601 Points

https://teamtreehouse.com/library/reporting-with-sql/aggregate-and-numeric-functions/counting-groups

dont know the answer

1 Answer

Steven Parker
Steven Parker
225,727 Points
Steven Parker
Steven Parker
225,727 Points

Task 1: 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.

Hints:

  • genre_count will be an alias given to a counting function
  • GROUP BY will be used to display each genre only once

And if you still can't get it...

:warning: SPOILER ALERT

SELECT genre, COUNT(*) AS genre_count FROM books GROUP BY genre;
Steven Parker
Steven Parker
225,727 Points
Steven Parker
Steven Parker
225,727 Points

Task 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.

Hints:

  • total_genres will be an alias given to a counting function
  • the counting function will use a special keyword to count only unique genre names

And if you still can't get it...

:warning: SPOILER ALERT

SELECT COUNT(DISTINCT genre) AS total_genres FROM books;