.. avmetadata::
   :author: Noha
   :satisfies: Relational Data Model
   :topic: Relational Data Model

Relational Data Model / Relational Database Diagram (RDD)
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Definition:
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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.

Terminology and Basic Concepts realated to RDD:
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 .. odsafig:: Images/RDDTerminology.png

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

.. odsafig:: Images/RelationSchema.png


.. odsafig:: Images/DatabaseSchema.png
.. odsafig:: Images/FDBSchemaLab.png

.. odsafig:: Images/Relation.png

.. odsafig:: Images/DatabaseInstance.png

.. odsafig:: Images/DatabaseState.png