database - May a 6NF Table contain a foreign key? -


does table satisfy 6nf when it's domain foreign key? e.g.:

create table authors(     author_id serial not null primary key );  -- other author attributes  create table books(     book_id serial not null primary key );  create table books_author(     book_id int not null primary key references books (book_id),     author_id int not null references authors (author_id) );

if no, how should model handle foreign key relationship?

and if relation m2m, how should handled? should join table 6nf?

6nf means relvar satisfies no non-trivial join dependencies, means has candidate key , at-most 1 other attribute. there may or may not foreign keys. normal forms unrelated whether foreign keys defined.

not sure question m2m is. when , use 6nf depends on motivation using in general. main use data warehouse , temporal data models.


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