Database Design Methodologies has phases to guide the designer for assistance. The Methodology has a structured approach to help in the design process.
The following are the phases/ models −
The Conceptual phase lets you know the entities and the relation between them. It describes the conceptual schema. The entities & relations are defined here.
Logical data model provides details about the data to the physical phase. The physical process gives ER Diagram, data dictionary, schema, etc that acts as a source for the physical design process.
The physical database design allows the designer to decide on how the database will be implemented.