Database Administrator: The mean who contort data program and data structure centrally is called database administrator. The following are his duty.
- Schema
Definition
- Storage
structure and access method
- Schema
and physical organization modification
- Granting
of authorization for data access.
Entity set: Entity Set is collection of similar entity which has similar properly or attribute.
Relationship: Relationship is association of among entity.
Primary Key: The unique identifier by which we can identify entity differently from entity set.
Super Key:
Network Data Model : The data model
which is express by collection of records and relation is represented links is
called network data model. It do not support many to one relationship.
Hierarchical Data model: The data model
which is express by collection for records and relation is represented links is
called hierarchical Data model. It support to one relationship.
- Data Structure Diagram: Data Structure
diagram is the schema of network data model.
- Tree structure Diagram: Tree structure
diagram is the schema of hierarchical Data model.
- Relational Data Model: The Data model
which represent data by collection of table is called relational data
model.
The following are database system:
- Server database system
- Client server database system
- Distributed database system.
