Database Schemas
Database systems link complex data structures. thus helping the system to retrieve data and store data in the database and also reduce the complexity of the users, developers.
There are mainly three levels of schemas in database concept, They are,
- Internal level
- Conceptual level
- External level
The internal schema tells all about the physical storage structure of the database.
The internal schema tells us what data are stored in the database and how they are stored in a database.
The internal schema is also known as a physical schema.
The physical level is used to describe complex low-level data structures in detail.
The Physical Level Is Do's Following Activities.
1) Storage space allocations.
2) Access paths.
3) Datacompression and Encryption Techniques.
4) Optimization Of Data Structures
Conceptual Level/Schema
The conceptual schema describes the database structure of the whole database for the community of users.
The conceptual level describes what data are to be stored in the database and also describes what relationship exists among those data.
Mostly programmers and database administrators work at this level.
Major Activities Of Conceptual Schema
1) Defines all database their entities, attributes, relationships
2) Provide security and integrity to our data.
External Schema/Levels
The external schema describes the part of the database in which a specific user is interested in it.
An external schema is also known as a view schema.
Each external view is defined using an external schema, which consists of definitions of various types of external records that are stored in database.
Activities of External Schema
1) External schema are related to the data which is viewed by specific end users.
2) This level includes some external schemas.
3) External schema is nearest to the user.
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