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Databases Reporting with SQL Aggregate and Numeric Functions Counting Groups


SELECT COUNT(genre) FROM books GROUP BY "genre_count";

1 Answer

First try to understand what you need to deliver, you need to count all books from difrent genres so :

  1. you need to select genre as genre count from table books .
  2. now we know what genres we have , and we need to count all of them,
  3. we have some books that genres dupplicates , i mean one genre can have mmultiple books , so we use group by

now lets write a query:

  1. select genre as genre_count from books
  2. select genre,count(*) as genre_count from books
  3. select genre,count(*) as genre_count from books group by genre;