In fairness, if this was in a relational data store, the same code as above would probably look more like...
SELECT DISTINCT authors.some_field FROM books
JOIN authors ON books.author_id = authors.author_id
WHERE books.pageCount > 1000
And if you wanted to grab the entire authors record (like the code does) you'd probably need some more complexity in there:
SELECT * FROM authors WHERE author_id IN (
SELECT DISTINCT authors.author_id FROM books
JOIN authors ON books.author_id = authors.author_id
WHERE books.pageCount > 1000
)
SELECT DISTINCT authors.some_field FROM books JOIN authors ON books.author_id = authors.author_id WHERE books.pageCount > 1000
And if you wanted to grab the entire authors record (like the code does) you'd probably need some more complexity in there:
SELECT * FROM authors WHERE author_id IN ( SELECT DISTINCT authors.author_id FROM books JOIN authors ON books.author_id = authors.author_id WHERE books.pageCount > 1000 )