JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2021 DATABASE MANAGEMENT SYSTEMS Previous Question Paper (July/August - 2021 - R17)

A data model is a collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints. The primary data models are:

• Relational Model: Uses a collection of tables (relations) to represent both data and the relationships among those data. Each table has multiple columns with unique names.
• Entity-Relationship (E-R) Model: Based on a perception of the real world as a set of basic objects called entities and relationships among them. It is widely used for database design.
• Object-Oriented Data Model: Extends the E-R model with notions of encapsulation, methods, and object identity, allowing for complex data types and inheritance.
• Semi-structured Data Model: Permits the specification of data where individual data items of the same type may have different sets of attributes, commonly represented using XML or JSON.

Database users and administrators are categorized based on their interaction with the system:

• Database Administrators (DBA): Professionals responsible for the overall control of the database system. Their duties include schema definition, storage structure and access method definition, schema and physical organization modification, granting authorization for data access, and routine maintenance.
• Sophisticated Users: Users who interact with the system without writing programs, instead using database query languages like SQL to request complex operations.
• Application Programmers: Developers who write application programs in languages like C++, Java, or Python to interact with the database using Data Manipulation Language (DML) calls.
• Naïve (Parametric) Users: Users who interact with the system by invoking one of the permanent application programs that have been written previously, such as bank tellers or web-based interface users.