The Three-Schema Architecture
In this lesson, we will define the three levels of data abstraction.
The three-schema architecture
The goal of the three-schema architecture is to separate the user applications from the physical database.
In this architecture, schemas can be defined at the following three levels:
1. External schema
An external schema describes the part of the database that a specific user is interested in. It hides the unrelated details of the database from the user like the exact process of retrieving or storing data from the database. There is a different external view for ...