dbms_class _14

DATABASE MANAGEMENT SYSTEM(DBMS) – CONCEPTS

AND APPLICATIONS

Prof. Ashis Mitra

St. Xavier’s College, Kolkata

28-04-2014 HRIS,ST.Xavier's College

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Recruiting Hiring Education & Training

Terminat- ion

Benefit Administration

Potential Employees Employees Retired

Employees

Data Management

The Firm

Primary HR Activities

DATA PROCESSING SYSTEM

A data processing system takes raw data and, through the power of computer automation, produces information that a set of program applications has validated. Information includes text, arithmetic calculations, formulas and various other types of information and data based on the computer system.

HRIS,ST.Xavier's College

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28-04-2014

TYPES OF DATA PROCESSING

1. Serial Processing

2. Batch Processing

3. Real time processing

4. Online Processing

5. Centralised Processing

6. Distributed Processing


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• 1. Serial Processing. It is a system in which only one step happens at a time (and so the steps

go in a series).

• 2. Batch Processing. It is used when there is a lot of transactions affecting a high percentage

of master file records and the response needed is not immediate, usually until the end of the

week or month. A good example of this in a large, national business would be payroll

processing, where nearly every master file record will be affected. The data is collected over a

period of time, then input and verified by clerks (verified means input by someone else and

then both inputs are compared by computer) and processed centrally.

• 3. Real-time processing. The waiting time from input to response is minimum. Unreasonable

However such fast systems are used in critical systems that control aircraft or the

manufacture of sensitive or dangerous compounds.


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• 4. Online processing. It means users directly enter information online (usually, online, in this case, means online to a central processor, rather than its modern connotation of the Internet, but it could mean both), it is validated and updated directly onto the master file. No new file is created in this case. Therefore, there is near immediate input process, and output. It is like a booking with travel agents or over the Internet.

• 5. Centralized processing. It is processing performed in one computer or in a cluster of coupled computers in a single location. Access to the computer is via "dumb terminals," which send only input and receive output or "smart terminals," which add screen formatting. All data processing is performed in the central computer.

• 6. Distributed Processing. The distribution of applications and business logic across multiple processing platforms. Distributed processing implies that processing will

• occur on more than one processor in order for a transaction to be completed.


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WHAT IS A DATABASE?

Database is a collection of interrelated data stored in a

database server; these data's will be stored in the form of

tables. The primary aim of database is to provide a way to store

and retrieve database information in fast and efficient manner.


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DATABASE – MAJOR CHARACTERISTICS

• In database approach, a single repository of data is maintained that is defined once and then accessed by many users.

• The database system not only contains data but it contains complete definition or description of the database structure and constraints. These definitions are stored in a system catalog, which contains the information about the structure and definitions of the database.

• The information stored in the catalog is called the metadata, it describes the primary database.

• Database allows multiple users to access the database at the same time and sharing of data is possible.

• Database software allows data to be accessed in a variety of ways and often, by using several programming languages.


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“CRUD”

Refers to the most common Database Operations:

Create

Read

Update

Delete

Operations occur at all levels: Tables, Records, Columns

A DATABASE WITH MULTIPLE TABLES

Training Employee Pay Packet

Placement Perform. Mgt Pay Structure


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DATABASE DESIGN

is a model of structures of reality

supports queries and updates

modeling processes of reality

runs efficiently

The purpose of database design is to create a

database which


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ABSTRACTION

Classification

Aggregation

Generalisation

It is very important that the language used for

data representation supports abstraction.

There are three kinds of abstraction:


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CLASSIFICATION

In a classification we form a concept in a way

which allows us to decide whether or not a

given phenomena is a member of the extension

of the concept.

Employee

Emp 1 Emp 2 Emp 3 Emp 4 Emp 5 Emp 6


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AGGREGATION

In an aggregation we form a concept from existing

concepts. The phenomena that are members of

the new concept’s extension are composed of

phenomena from the extensions of the existing

concepts

Company

Operation

Marketing

Finance


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GENERALIZATION

In a generalization we form a new concept by

emphasizing common aspects of existing concepts,

leaving out special aspects

Employee

Jr. Executive Executive Sr. Executive


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LEVELS OF ABSTRACTION

Physical level describes how a record (e.g., customer) is stored.

Logical level: describes data stored in database, and the relationships among the data.

type Employee = record name : string; Designation : string; EMP Code : integer; end;

View level: application programs hide details of data types. Views can also hide information (e.g., salary) for security purposes.


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DATABASE VIEWS

A View is an individual’s picture of a database. It can be

composed of many tables, unbeknownst to the user.

It’s a simplification of a complex data model

It provides a measure of database security

Views are useful, primarily for READ-only users and are not always safe

for CREATE, UPDATE, and DELETE.

VIEW OF DATA

An architecture for a database system


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USE OF A DATABASE MANAGEMENT SYSTEM

IN DESIGN AND APPLICATION

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Design

Analysis

Design

Verification Evaluation Synthesis Release

HR

Planning HR

Admin

HR

Dev

APPLICATION

DBMS

Database Management

System

Graphic Interface Language Interface INTERFACE

Preliminary-

design

Analysis

Models

Detailed

Design

Design

Release

Control Fabrication

Assembly

Info

Test /

Inspection

Database Manufacturing


PEOPLE WORKING WITH DATABASES

System Analysts

Database Designers

Application Developers

Database Administrators

End Users


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SYSTEM ANALYSTS

communicate with each prospective database user group in order to understand its

information needs

processing needs

develop a specification of each user group’s information and processing needs

develop a specification integrating the information and processing needs of the user groups

document the specification


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DATABASE DESIGNERS

choose appropriate structures to represent the information specified by the system analysts

choose appropriate structures to store the information in a normalized manner in order to guarantee integrity and consistency of data

choose appropriate structures to guarantee an efficient system

document the database design


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APPLICATION DEVELOPERS

implement the database design

implement the application programs to meet the program

specifications

test and debug the database implementation and the

application programs

document the database implementation and the application

programs


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DATABASE ADMINISTRATORS

Manage the database structure

participate in database and application development

assist in requirement analysis

participate in database design and creation

develop procedures for integrity and quality of data

facilitate changes to database structure

seek communitywide solutions

assess impact on all users

provide configuration control

be prepared for problems after changes are made

maintain documentation


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DATABASE ADMINISTRATORS (CONT.)

Manage data activity

establish database standards consistent with data administration

standards

establish and maintain data dictionary

establish data proponencies

work with data proponents to develop data access and modification

rights

develop, document, and train staff on backup and recovery procedures

publish and maintain data activity standards documentation


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DATABASE ADMINISTRATORS (CONT.)

Manage the database management system generate database application performance reports

investigate user performance complaints

assess need for changes in database structure or application design

modify database structure

evaluate and implement new DBMS features

tune the database

Establish the database data dictionary data names, formats, relationships

cross-references between data and application programs

(see metadata slide)


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END USERS

Parametric end users constantly query and update the database. They use canned transactions to support standard queries and updates.

Casual end users occasional access the database, but may need different information each time. They use sophisticated query languages and browsers.

Sophisticated end users have complex requirement and need different information each time. They are thoroughly familiar with the capabilities of the DBMS.


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