Dbms_class _14

DATABASE MANAGEMENT SYSTEM(DBMS) – CONCEPTS
AND APPLICATIONS
Prof. Ashis Mitra
St. Xavier’s College, Kolkata
28-04-2014HRIS,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
3
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. ExecutiveExecutiveSr. 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
1-19
Design
Analysis
Design
Verification
Evaluation Synthesis Release
HR
Planning
HR
Admin
HR
Dev
APPLICATION
DBMS
Database Management
System
Graphic Interface Language InterfaceINTERFACE
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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Dbms_class _14

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