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Design Methodologies | Types of Design Methodologies | DBMS

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Design Methodologies | Types of Design Methodologies | DBMS

Design methodologies: Design methodologies are basically the technique used to design the system. The design methodology attempts the following;

  • Improve productivity of analysis & programmers
  • Improve documentation
  • Improve communication among user, analyst & programmer
  • Cut down drastically on cost overruns and delay

The methodologies of system design are given below

  1. Structured Design

Structured design is the most popular methodology for developing new designs.

Structured design is a data flow based methodology.

In this methodology, the software is considered as a transformation function that converts the given inputs into desired outputs.

Structured design divides the system into small manageable modules that are arranged in a hierarchy & organised into top-down manner.


Coupling is the strength of interconnections between modules.


Cohesion is the strength of different elements within a module.


  1. Critical interfaces are tested first.
  2. Structuring the design, provides control & improves morale.
  3. The procedural characteristics define the order that determines processing.


It does not model the real life system.


  1. Forms Driven-Methodology (HIPO and IPO Charts)

HIPO, stands for Hierarchical Input Process Output, It consists of two types of diagrams:

Visual Table of contents (VTOC)

VTOC diagrams breaks a system down into increasingly detailed levels. Therefore, the name of the system appears at the top of the VTOC. The VTOC for assembly of a bicycle.

Design Methodologies | Types of Design Methodologies | DBMS


An IPO chart defines the inputs, processing & outputs for each module in the program.


Structured Walkthrough

An activity of all phases of a structured project is the walkthrough, It is an interchange of ideas among peers who review a product presented by its author & agree on the validity of proposed solution to a problem.




A database system consists of collection of interrelated data & the software system that is used to manage the database is called database management system(DBMS).


Components of DBMS/ Structure of DBMS

The DBMS contains the following components

  1. Data Definition Language Compiler

The DDL compiler converts the data definition statements into set of tables. This table contains the metadata concerning the database.

  1. Data Manager

Data Manager convert operation in the user’s queries from the user’s logical view to a physical file system. The data manager is responsible for interfacing with the file system.

  1. File Manager

The file manager is responsible for maintaining the structure of the files & file space.

  1. Disk Manager

The disk manager is responsible for transferring the block or page requested by the file manager.

  1. Query Processor

The query processor is used to interpret the online user’s query & convert it into an efficient series of operations in a form capable of being sent to the data manager for execution.

  1. Telecommunication System

Online users of a computer system, whether remote or local communicated by sending & receiving messages over communication lines by using an independent software system called a communication system.

  1. Data files

Data files contain the data portion of the database.

  1. Data Dictionary

The data dictionary contains data about data. The data dictionary contains information about entity, attributes, mapping & cross-reference information.

  1. Access Aids

A set of access aids in the form of indexes are usually provided to improve the performance of the DBMS.


Function of DBMS

  1. Data Definition

The DBMS must be able to define the data i.e. accept the data definition &convert it into appropriate object form.

  1. Data Manipulation Language

DBMS must be able to manipulate data.

  1. Data Security & Integrity

DBMS must monitor uses request & reject any attempt to violate the security & integrity rules defined by the DBA.

  1. Data Dictionary

It contains data about data.

  1. Performance

DBMS should perform all the functions identified above as efficiently as possible.


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