B, in the conceptual design stage: described by e-r diagram.

C. In the logic design stage, the e-r diagram is transformed into a data model supported by a specific database product, such as a relational model, to form a database logic model. Then, according to the user's processing needs and security considerations, the necessary views are established on the basis of the basic table to form the external mode of data.

D, in the physical design stage: according to the characteristics of dbms and the needs of processing, arrange physical storage, design indexes, and form patterns in the database.

As soon as it unfolds, it will be enough on paper.