Introduction to Database System

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Introduction to Database System

Introduction to Database System

  • A database Management System is a collection of interrelated data and a set of programs to access those data.
  • The primary goal of a DBMS is to provide an environment that is both convenient and efficient for people to use in retrieving and storing information.
  • Database system is ubiquitous today, and most people interact, either directly or indirectly with database many times every day.

Applications of Database System:

Shopping Malls
Medium/Large Scale Business

Disadvantages of File Processing Systems

  • Data Redundancy and inconsistency
  • Difficulty in accessing data.
  • Data isolation.
  • Integrity problems.
  • Atomicity problems.
  • Concurrent Access anomalies.
  • Security issues.

Structured Query Language is used for communicate between your interface and database.

Data Abstraction: The system hides certain details of how the data are stored and maintained.

  • Physical Level Abstraction: How the data are actually stored.
  • Logical Level Abstraction: What data are stored in the database and what relationship among those data.
  • View Level: Only part of the data is visible.

The collection of information stored in the database at a particular moment is called an instance of the database.

The overall design of the database is called the database schema.

  • Physical Schema.
  • Logical Schema.

Data Models: A collection of conceptual tools for

  • Describing data,
  • Data relationships,
  • Data semantics and
  • Consistency constrains.

Categories of Data Models:

  • Relational Model
  • The Entity – Relationship Model
  • Object based data model
  • Semi structured data model.

A Query is a statement requesting the retrieval of information.

The portion of a DML that involves

Database Languages:

  • Data Definition Language (DDL):
  • Data Manipulation Language(DML):
    • Retrieval of information stored in the database.
    • Insertion of new information.
    • Deletion of information.
    • Modification of information.


Data Storage and Querying: Database system is broadly divided into storage manager and query processor.

Storage Manager: A storage manager is a program module that provides the interface between the low level data stored in the database and the application programs and queries submitted to the system.

  • Storage Manager (Physically: Data Files, Data Dictionary, Indices)
    • Authorization and integrity manager.
    • Transaction manager
    • File Manager
    • Buffer Manager
  • Query Processor
    • DDL interpreter
    • DML compiler
    • Query Evaluation Engine.
  • Transaction Management.

Different Types of Users:

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  • Naïve Users
  • Application Programmers
  • Sophisticated Users.
  • Specialized Users.

Functions of Database Administrators:

  • Schema Definition
  • Storage structure and access method definition.
  • Schema and physical organization modification.
  • Granting of authorization for data access.
  • Routine maintenance.

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