Write an SQL query to select the names of the three most read authors currently (those with the most books on hand).

Suppose we have the following tables:

• authors (id, name)
• books (id, author_id)
• loans (id, book_id, loan_date, return_date)

To select the names of the three authors who currently have the most books on loan (i.e., books that are borrowed and not yet returned), you can write the following query:

SELECT a.name, COUNT(*) AS books_on_loan
FROM authors a
JOIN books b ON a.id = b.author_id
JOIN loans l ON b.id = l.book_id
WHERE l.return_date IS NULL
GROUP BY a.id, a.name
ORDER BY books_on_loan DESC
LIMIT 3;

This query counts the number of books for each author that are currently not returned (return_date IS NULL), sorts the results in descending order, and retrieves the top 3.