JNTU B.Tech III DATABASE MANAGEMENT SYSTEMS Previous Question Paper (July/August - 2023 - R16)

Data independence refers to the ability to modify the schema definition at one level of a database system without requiring changes to the schema definitions at the higher levels. It ensures that the application programs remain unaffected by changes in the underlying data storage or structure.

There are two types of data independence:

• Logical Data Independence: The ability to change the logical schema (conceptual level) without having to change the external schema (view level) or application programs.
• Physical Data Independence: The ability to change the physical storage structures or access methods without affecting the logical schema or the application programs.

The major components used in Entity-Relationship (E-R) diagram design are:

• Entities: Represent real-world objects or concepts that have independent existence. They are depicted using rectangles and contain attributes.
• Attributes: Represent the properties or characteristics of an entity. They are depicted using ovals and include key attributes (underlined), composite attributes, and multi-valued attributes.
• Relationships: Represent the associations or interactions between entities. They are depicted using diamonds and are defined by their cardinality constraints, such as one-to-one, one-to-many, or many-to-many.