---

Table books {
  id integer [pk]
  title varchar
  year integer
  pages integer
  price decimal
  genre_id integer [ref: > genres.id]
  publisher_id integer [ref: > publishers.id]
}

Table authors {
  id integer [pk]
  name varchar
}

Table book_authors {
  book_id integer [ref: > books.id]
  author_id integer [ref: > authors.id]

  indexes {
    (book_id, author_id) [pk]
  }
}

Table genres {
  id integer [pk]
  name varchar
}

Table publishers {
  id integer [pk]
  name varchar
  city varchar
}

Table suppliers {
  id integer [pk]
  name varchar
  contact_info varchar
}

Table deliveries {
  id integer [pk]
  date date
  document_number varchar
  supplier_id integer [ref: > suppliers.id]
}

Table delivery_items {
  id integer [pk]
  delivery_id integer [ref: > deliveries.id]
  book_id integer [ref: > books.id]
  quantity integer
}

Table sales {
  id integer [pk]
  date date
}

Table sale_items {
  id integer [pk]
  sale_id integer [ref: > sales.id]
  book_id integer [ref: > books.id]
  quantity integer
  total_amount decimal
}