sample.erd

User : All our customers {
  id
  email varchar(128) : User's email address
  name : user's name
}

Post {
  id
  blog_id -> Blog.id
  category_id -> Category.id
  title : title of the blog post
  text : plain text content of the blog post
}
    
Blog {
  id
  user_id -> User.id
  name
}

Category {
  id
  name
  parent_category_id ..> Category.id
  blog_id -> Blog.id
}