Exercise

Summarizing the data

You are a developer for the Metropolitan Public Library. The head librarian has requested a new feature for the online catalog: displaying rating statistics for each book to help patrons make informed reading choices. Currently, the system stores individual reviews in the book_reviews table; however, there's no way to view the total number of reviews a book has received or its average rating.

Your task is to write a query that summarizes review data by calculating the total number of reviews and the average rating for each book.

Instructions

100 XP

Complete the query to count the number of reviews and calculate the average rating.
Group the results by book_id to get statistics for each book.

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Instructions

Exercise