PlantUML — Chen ER

@startchen
title Library System (Chen notation)

entity STUDENT {
  student_id <<key>>
  name
  email
}
entity BOOK {
  isbn <<key>>
  title
  year
}
entity LIBRARIAN {
  staff_id <<key>>
  name
}

relationship BORROWS {
  date
}

STUDENT -1- BORROWS
BORROWS -N- BOOK
LIBRARIAN -1- BORROWS
@endchen