Abstract
Conceptual data modeling extracts a data structure from a target domain by creating an entity-relationship model
(ERM), which is converted into a normalized relational database model. Such normalization is a process after extracting
the data structure. On the other hand, we change this perspective and clarify the required ERM structure for generating a
database model with a third normal form (3NF). An ERM should be composed of (1) associations with at least one
multiplicity of “1” and (2) entities whose non-key attributes are in the 3NF. Additionally, the ERM structure should be a
Hasse diagram: an irreducible directed acyclic graph. We also propose an Entity Action Dependency Diagram (EADD),
which is a template for simply designing our proposed ERM. Our proposed EADD/ERM structure is a necessary and
sufficient condition to generate 3NF databases.
