Three Views & Schemes of DBMS

Database Schema  

A database schema is the skeleton structure that represents the logical view of the entire database. A database schema defines its entities and the relationship among them.

A database schema can be divided broadly into two categories –

     Physical Database Schema

     Logical Database Schema

Three-schema architecture

          ·              Internal level:     It is also known as physical level.

          ·              Conceptual level:        It is also known as logical level.

          ·              External level:    It is also known as view level. 

Data independency

        1.    Logical data independence

        2.    Physical data independence

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