DB Architecture & DB Access

DB Architecture/ 3-Layered Architecture:

1)   External Layer or View Layer:

It is the end user perspective of the data without any concern about how the data is stored in db, where in the db it is stored, how many tables are required to fix these data, and what relationship do exist among the tables.

2)   Conceptual Layer or Logical Layer:

This level defines the relationship between tables or object that exists among various entities, attributes/values, so that all the records are consistence and integrity of the data is maintained.

It prevents inconsistency and the integrity of the data can be maintained.

(This layer defines the relationship between the entities, attributes, tables so that all the consistency and integrity of the data can be maintained.)

3)   Physical Layer or Internal Layer:

This layer in db system tells where to store, how much memory is required etc.

It is concerned with defining storage space to db files.

DB Access