Fundamentals of Data Analysis Counting books users started to read in the first week

39. Counting books users started to read in the first week

That was a looong journey to answer Linh’s question about user activity. The association between users and books is many-to-many, it means there’s a join table named books_users with both foreign keys from the users table (user_id) and books (book_id). Here’s the table’s structure:

user_id book_id last_page created_at
2305 470 37 2019-07-24 20:05:37.660917
2319 45 146 2019-07-24 20:05:37.707183

Every time a user starts reading a new book a new record to the books_users table is added. The created_at column has a precise date when the...

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-- Type in your query here. You might want to start by listing all records: SELECT * FROM books_users
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