Database Core Concept

Three-Schema Architecture

Internal Schema

·         Description of Physical Storage structure of the database.

·         It has an internal Schema

·         It descried the details of the store records and access method used to achieve efficiency to data.

Conceptual level                                        

·         This hides the details of physical storage structure

·         This level is both independent of software and hardware

External Level or  view level

·         This the outer most layer

·         This layer is closet to the users

·         Data can be view by individual users

Dbms must have a programming language

Dbms Language
DDL---Data Defination Language
DML—Data Manupulation language

Data Manupulation Language: