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The Three-Schema Architecture

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 ...