Database MN relationship

Question

I\'m taking a class on database management systems (absolute beginner) and I\'m working on a database for a very simple blog system.

I have a question regarding one M:

Answer 1

It's probably a combination of two things. One would be a lack of referential integrity in your database design, ie you need foreign keys. The other would be that your front end application is allowing blogs without categories to be posted.

Answer 2

Because you can add a blog_posts record without having to add an associated post_cat record.