Comment by eirki

> Avoid

  SELECT
    title,
    last_name,
    first_name
  FROM books
    LEFT JOIN authors
    ON books.author_id = authors.id

> Prefer

  SELECT
    b.title,
    a.last_name,
    a.first_name
  FROM books AS b
    LEFT JOIN authors AS a
    ON b.author_id = a.id

Couldn't disagree more. One letter abbreviations hurt readability IMO.