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Session Objectives

Data, Processing & Information

The Role of Data in Business

 Meta Data& Metameta Data

 What is a Database

 Evolution of databases

Types of files

 Traditional File Processing Systems

Types of DBMS

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Introduction

Data:

• “A collection of raw facts and figures”.

• “Data consists of facts, text, graphics,

images,sound and video.”

Definitions

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Figure 1-1a Data in Context

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Information

• Information:

• Data processed to be useful in decision making.

• Information is, processed data that is correlated and meaningful.

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Figure 1-1b Summarized data

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Metadata: Data that describes data.

Name Type Length Min Max Description

sId Character 11 11 11 Student Id

cId Character 8 8 8 Course Id

Section Integer 1 1 9 Section Number

Year Integer 4 1980 2100 Year Completed

Term Integer 4 1 4 Semester

Grade Character 1 Alpha Grade: Must be in (A,B,C,D,F,I)

Example

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Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and

data context

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“Data about a metadata record”  Information about a metadata record, such as when that record was created, by whom, and when it was last updated, is called metametadata

MetaMeta Data

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Data Vs Information

Data are….. Information is….

1.Stored facts 1. Presented facts

2.Inactive (They exist) 2.Active (It enables doing)

3.Technology –based 3.Business Based

4.Gathered from various sources

4.Transformed from data

5.Refers to the values actually stored in.

5. Refers the meaning of the values as understood by some users

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DATABASE

1. A database is an organized collection of logically related data.

2. A database is a computerized record keeping system.3. “A database is a collection of inter-related records with minimum of data redundancy.”

4. Collection of related data items that are being stored for record-keeping & analysis

Could be stored on cards ,file cabinet, computer, …

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A collection of related files.

A collection of records about a particular set of people, objects, entities and so on.

A collection of related fields associated with a single person, object, entity and so on.

A collection of bytes representing a single attribute.

A collection of bits representing a single character.

A binary digit.

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3. A database is a self-defined collection of integrated files.

Integrated : It is possible to navigate from file to file to extract necessary information.

Note: A FILE is a collection of logical records in a tabular format.

A RECORD contains fields (or attributes ) about the entity. A field is same as an ‘attribute’

Implicit properties

Have a Source

Degree of interaction

Audience

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SLSREP Slsrep Name Commission TotalNumber Rate Commission3 Mary Jones .05 2150.006 Bill Smith .07 4912.0012 Sam Brown .06 3567.80

CUSTOMER Cust# Name City Balance Credit Slsrep#

124 Sally Adams Delta 418.75 500.00 3256 Ann Samuels Tiffin 10.90 800.00 6311 Don Charles Toledo 200.10 300.00 12315 Tom Daniels Toledo 320.75 300.00 6405 Al Williams Swanton 408.87 800.00 3412 Sally Adams Toledo 201.20 500.00 12

ORDERS

Order# Date Cust#

2561 07/11/94 2562562 12/12/94 2563111 05/16/95 3113112 08/01/95 311

ORDER DETAILOrder# Part# Qty Selling Price

2561 P110 10 154.562561 P120 20 234.002562 P110 20 150.203111 M075 1 1200.703111 P110 5 165.893112 M075 10 1120.00

PRODUCT Product# Description Qty. on Hand Unit Price

P005 5 GPM Pump 456 78.98P110 10 GPM Pump 100 178.89P120 20 GPM Pump 50 278.98M010 10 HP Motor 8 767.00M075 75 HP Motor 5 1150.00

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Databases

• Web indexes• Library catalogues• Medical records• Bank accounts• Stock control• Personnel systems• Product catalogues• Telephone

directories

• Train timetable• Airline bookings• Credit card details• Student records• Customer histories• Stock market prices• And so on….

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Types of Files• Master File“A master file is a relatively permanent file relating to a standard. The

records changes less frequently. “Example:Customers, student’s, employee’s

• Table File“A table file contains references data used by information system.These

are relatively permanent. Updated by periodically.”Example: Tax table, postage rate tables, department code file

Transaction File:It contains records reflect day-to-day activities.These are temporarily files.Example: New employees, patient release, cash receipt, commission and

customer payments

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• Security File

“Is a file that is created and saved for backup and recovery purposes. New security files must be created periodically to replace old, outdated security files.”

• History File“Is a file created and saved historical reasons. Don’t replace

old files;usually both the old and new history files are saved.”

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File-Based Approach

• A collection of application programs that perform services for the end-users such as the production of reports. Each program defines and manages its own data.

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What is File Processing SystemsFile: a collection of related information defined by its creator.

Physical file: a file actually exists in a storage devise.

( a collection of bites, as seen by the operating system.)

Logical file: a file viewed by users and programs.

( a collection of records.)

A file management system, usually within the operating system, is

used to efficiently access physical files stored in the secondary storage

devices.

Functions: create, updates, retrieval

Examples: Hard copy registers/folders,bill folder, tax folder

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Figure Three file processing systems

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Disadvantages of File Processing

• Program-Data Dependence– All programs maintain metadata for each file they use

• Data Redundancy (Duplication of data)– Different systems/programs have separate copies of the same

data

• Limited Data Sharing– No centralized control of data

• Lengthy Development Times– Programmers must design their own file formats

• Excessive Program Maintenance– 80% of of information systems budget

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Figure 1-2 Three file processing systems

Duplicate Data

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Uncontrolled redundancy

Inconsistent data

Inflexibility

Limited data sharing

Poor enforcement of standards

Excessive program maintenance

Excessive data maintenance

File formatting issues

Recovery

Disadvantages File Management Systems

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Empno Name Job Salary Join-Date Deptno Dept-name

100 Allen Manager 4500 25-Jan-89 3 Marketing

101 John Analyst 3000 13-Mar-92 2 Research

102 Diane Clerk 2000 04-Jul-94 1 Sales

103 Adam Clerk 2000 15-Mar-93 2 Research

Accounts Department

Name Address Tel-No join-Date Birth-Date

Designation

Salary

Allen Aaa 1234 25-Jan-89 25-Jan-49 Manager 4500

John bbb 2345 13-Mar-92 13-Mar-52 Analyst 3000

Diane ccc 3456 04-Jul-94 04-Jul-74 Clerk 2000

Human Resources Department (HRD)

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Problems with Data Dependency Each application programmer must maintain their

own data Each application program needs to include code

for the metadata of each file Each application program must have its own

processing routines for reading, inserting, updating and deleting data

Lack of coordination and central control Non-standard file formats

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Problems with Data Redundancy

• Waste of space to have duplicate data

• Causes more maintenance headaches

• The biggest Problem: – When data changes in one file, could cause

inconsistencies

– Compromises data integrity

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SOLUTION: The DATABASE Approach

• Central repository of shared data

• Data is managed by a controlling agent

• Stored in a standardized, convenient form

Requires a Database Management System (DBMS)

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Database SystemsA database system

Consists of– Data(The database)– Software– Hardware– Users

We focus mainly on the software

Database systems

Allow users to– Store– Update– Retrieve– Organize– Protect

their data

The database and DBMS software together make up what is known as the Database System

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Database Management System

• A DBMS is a data storage and retrieval system which permits data to be stored non-redundantly while making it appear to the user as if the data is well-integrated.

Collection of programs that allows users to create a new database and specify its structure gives users the ability to query and modify the data efficiently keeps the data secure from accidents or unauthorized use controls the access to the data for many users at once

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DBMS is a tool to ease the construction of database

“ A software system that facilitate the creation and maintenance and use of an electronic database.”

According to Oxford dictionary:

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Database Management System

DBMS manages data resources like an operating system manages hardware resources

DBMSDBMS Databasecontainingcentralized

shared data

Application#1

Application#2

Application#3

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Advantages of Database Approach

• Program-Data Independence – Metadata stored in DBMS, so applications don’t need to

worry about data formats– Data queries/updates managed by DBMS so programs don’t

need to process data access routines– Results in: increased application development and

maintenance productivity

• Minimal Data Redundancy– Leads to increased data integrity/consistency

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Advantages of Database Approach• Improved Data Sharing

– Different users get different views of the data

• Enforcement of Standards– All data access is done in the same way

• Improved Data Quality – Constraints, data validation rules

• Better Data Accessibility/ Responsiveness– Use of standard data query language (SQL)

• Security, Backup/Recovery, Concurrency– Disaster recovery is easier

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Costs and Risks of the Database Approach

• Up-front costs:– Installation Management Cost and Complexity– Conversion Costs

• Ongoing Costs– Requires New, Specialized Personnel– Need for Explicit Backup and Recovery

• Organizational Conflict– Old habits die hard

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Figure 1-10 Components of the database environment

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Components of the Database Environment

• CASE Tools – computer-aided software engineering• Repository – centralized storehouse of metadata• Database Management System (DBMS) – software for

managing the database• Database – storehouse of the data• Application Programs – software using the data• User Interface – text and graphical displays to users• Data Administrators – personnel responsible for

maintaining the database• System Developers – personnel responsible for designing

databases and software• End Users – people who use the applications and

databases

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What do you want from a DBMS?

Answer queries (questions) about data Update data And keep data around (Persistent)Example: A traditional banking application Each account belongs to a branch, has a number,

an owner, a balance,……Query: What’s the balance in Ali Traders

account?Modification: Ali traders withdraws 1000 Rs.Persistency: Ali will be pretty upset if his

balance disappears after power outage

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Some Recent TrendsDBMS are getting smaller and smaller– DBMS that can store GB of data can run on PC

Databases are getting bigger and bigger– Multiple TBs (terabyte = 1012 bytes) not uncommon– Databases also able to store images, video, audio– Database stored on secondary storage devices

DBMS Supporting Parallel Computing– Speed-up query processing through parallelism (e.g., read

data from many disks)– However, need special algorithms to partition data

correctly

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When NOT to Use a DBMS

• Initial investment too high

• Too much overhead

• Application is simple, well-defined, not expected to change

• Multi-user access to data is not required

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Types of DBMSGeneral-purpose DBMS: can store and accessed is either

textual or numeric

Multimedia DBMS: can now store pictures, video clips, and sound messages.

Geographic information systems (GIS): can store and analyze maps, weather data, and satellite images.

Data warehouse& OLAP DBMS: systems are used in many companies to extract and analyze useful information from very large databases for decision making.

Real-time DBMS: and active database technology is used in controlling industrial and manufacturing processes.

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Types of Databases

• Several strategies are available for deploying and using databases in organizations.

• There are two generic database architectures:

Centralized

Distributed

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Central Computer Database

“ If collection of data or facts are stored at single side is called centralized database.”

There are three common examples of

centralized databases:

A Personal computer databaseA central computer database

A Client/Server database 

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Personal Computer Database

“Single user database, which is used by single user. “

Common Applications:

Simple accounting system

Inventory used in small scale business

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Central Computer Database

The Data that most applications in large organizations access is stored on a central computer. Depending on the size of the organization, the central computer is usually a mainframe or a minicomputer. Central computer database often involve very large, integrated databases that must be accessed by a large number of users. Usage is often intense, with several hundred transactions per second being processed.

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Common Applications:

Airline reservation systems

Financial institutions

Express delivery companies

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Client/Server Database

“Client / Server architecture is designed for the distribution of work on a computer network in which many clients may share the services of a single server.”

Client/Server architecture has three components ClientServer

Network

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Client/Server Environment

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Benefits

Many clients can share resources

Clients’ applications can be designed with no dependency on the physical location of data.

Essay to manage concurrent access

Provide independence between applications components and reduce costs.

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Distributed Database

“Distributed database system is a set of database stored on more than one CPU in such a way that users precise the data as a single large database where as infect it is several smaller database.”

“A distributed database is a single logical database that spread physically across computer in multiple locations”

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Categories of Distributed Databases

“ When applied to databases, the term homogeneous means that the database technology is the same (or at least compatible) at each locations and that the data at various locations are also compatible “

The following conditions would probable exist:The computer operating systems used at each of the locations are the same, or at least they are highly compatible The data models used at each of the locations are the same. The database management systems used at each locations are the same, or at least they are highly compatible .The data at the various locations have common definitions and formats.

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Homogeneous Databases

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Heterogeneous Database

“When applied to databases, the term heterogeneous means that the database technology is not same at each locations and that the data at various locations are also not compatible “

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Heterogeneous Database