Relational Model

A Relational Model of Data for Large Shared Data Banks

E.F. Codd

Proposes that data be organised around relations rather than pointers, so applications are insulated from how the data happens to be stored.

Assumes basic set theory and predicate logic; no SQL, which did not exist yet and is not what this describes

Extending the Database Relational Model to Capture More Meaning

E.F. Codd

Extends Codd's own relational model with entity types, roles and multiple relationships, addressing criticism that the flat original model lost meaning the real world actually has.