Tell me about the blog DB structure!

I'd like to make a blog with PHP. I would like to create a personal blog of members like Naver blog, not a personal homepage. I have many questions about DB design before making it.

I don't think it was difficult to design the DB for my homepage or community site that I made at first. I think it was easy because it was divided into big categories like writing, comments, and categories.

Does a personal blog create a DB for each individual member when signing up? How do you manage categories?I'm so curious how you design it Help!