1.2.1. Definition:¶

Is a model that represents database in the form of two-dimensional tables with rows and columns of data These tables are called relations. Its a model based on the concept of sets.

A database usually contains more that one of these tables (relations).

Relational schema: means the way in which these relaions (tables) are descibed.

1.2.2. Terminology and Basic Concepts realated to RDD:¶

Basic definitions illustrated in the following figures based on faculty database example.