I want to make a system so a person can review a book. They get a list of chapters so they can edit each chapter individualy.

But there is another thing. Every reviewer is assigned to one book. They can't review more than one book.

Don't ask me why. Long story.

I am making an entity model diagram:
_______________
Costumers
PK CustId
username
password
______________
BookParts
BookId
ChapterNr
SubchapterNr
Text
reviewchapterdate

The combination of bookId, ChapterNr and SubChapterNr are always unique. How do i do this?

And is this the best way to store the books and chapters?

You can easily now make a search enigne dat search the text of all the books and chapters.