data & database

8/7/2019 data & database

1/23

Technology Guide 3

Data and Database

T3-1


2/23

IT for Management

Prof. Efraim Turban

T3-2

File Management

Hierarchy of data for a computer-based file

Record

Field Field

Byte Byte

Bit Bit

Record

FieldField

ByteByte

BitBit

File

Database

File


3/23

IT for Management

Prof. Efraim Turban

T3-3

File Management Entity

a person, place, thing, or event on which

we maintain information Attribute

characteristic or quality describing aparticular entity

corresponds to a field

Key Field a file that uniquely identifies that record

an identified filed


4/23

IT for Management

Prof. Efraim Turban

T3-4

Accessing Records from

Computer Files

Sequential File Organization

data records must be retrieved in thesame physical sequence in which theyare stored

magnetic tape

Direct or Random File Organization Users can access records in an

sequence, without regard to actualphysical order on the storage medium

magnetic disks


5/23


6/23

IT for Management

Prof. Efraim Turban

T3-6

Database and

Database Management Systems Database

an organized logical grouping of related files

no data redundancy, data isolation, and data

inconsistency

Database Management Systems (DBMS)

a program that provides access to a database

permits an organization to centralize data,

manage them efficiently, and provide access

to the stored data by application programs


7/23

IT for Management

Prof. Efraim Turban

T3-7

Specialized Database Geographical Information Database

contains locational data for overlaying on

maps or images

Knowledge Database

stores decision rules used to evaluate

situations and helps users make decisionslike an expert

Multimedia Database

Stores data on many media sounds,

video, images, graphic animation, and text


8/23

IT for Management

Prof. Efraim Turban

T3-8

Data Definition Language

(DDL)

Schema

the logical description of the entiredatabase and the listing of all thedata items and the relationshipsamong them

Subschema the specific set of data from the

database that is required by eachapplication


9/23

IT for Management

Prof. Efraim Turban

T3-9

Data Manipulation language

(DML)

Structured Query Language (SQL)

combines both DML and DDL features offers the ability to perform complicated

searches with relatively simple statements

Query-by-example (QBE) allows users to select a table and chooses

the fields to be included in the answer as

the example he provided


10/23

IT for Management

Prof. Efraim Turban

T3-10

Data Dictionary

Data dictionary is a file that storesdefinitions of data elements and

data characteristics such as usage,

physical representation, ownership,authorization, and security


11/23

IT for Management

Prof. Efraim Turban

T3-11

Hierarchical Database Model

It relates data by rigidly structuring data

into an inverted tree A single root or master field (Key)

identifies the type location, or ordering of

the records A variable number of subordinate fields

defines the rest of the data within a record


12/23

IT for Management

Prof. Efraim Turban

T3-12

Network Database Model

It creates relationships among data

through a linked-list structure inwhich subordinated records can be

linked to more than one parent

Pointers

link subordinates and parents

storage addresses that contain the

location of the related record


13/23

IT for Management

Prof. Efraim Turban

T3-13

Relational Database Model It is based on the simple concept of

tables in order to capitalize on

characteristics of rows and columns

of data, which is consistent with

real-world business situations

Relations : table Record : row of data

Field : column of data

Object-relational Database Systems


14/23

IT for Management

Prof. Efraim Turban

T3-14

Creating Database

Conceptual Design

an abstract model of the databasefrom the user or business perspective

Describes how the data elements in

the database are to be grouped

Physical Design

shows how the database is actually

arranges on direct access storage

devices


15/23

IT for Management

Prof. Efraim Turban

T3-15

Entity-relationship Modeling Entity is something that can be identified

in the users work environment

Instance of an entity is the representation

of a particular entity

Attributes describe the entitys

characteristics

Identifiers are attributes that identify

entity instances

Relationships can include many entities


16/23

IT for Management

Prof. Efraim Turban

T3-16

Entity-Relationship Diagram

Table

ClassStudent Professor

Name

ID Number

Major

Departmet

Class Taught

Name

Attribute

Entity Relationship

1:N

One to many


17/23

IT for Management

Prof. Efraim Turban

T3-17

Normalization of

Relational Databases

Functional Dependency

a relationship between or

among attributes, where,

given the value of one

attribute, we can obtain the

value of another attribute


18/23

IT for Management

Prof. Efraim Turban

T3-18

Emerging Database Models

Multimedia Database : an additionaldatabase that enables end users to quickly

retrieve and present completes data that

involve many dimensions

Deductive Databases

Object-oriented Database : used for OOprogramming

Multimedia and Hypermedia Database

: analogous to textual and numeric data


19/23

IT for Management

Prof. Efraim Turban

T3-19

Data Warehouses

It is an additional database that is designed to

support DSS, EIS, online analytical process(OLAP), and other end-user activities.

It can provide an executive view of data

and a unified corporate picture to the end-

users by combining the data from manyoperational systems and incompatible

databases without affecting the performance

of the running operational systems


20/23

IT for Management

Prof. Efraim Turban

T3-20

Database Topology Centralized Database has all the related

files in one physical location

Distributed Database has completecopies of a database, or portions of a

database, in more than one locations

Replicated Database has complete copiesof the entire database in several locations

Partitioned Database is subdivided, sothat each location has a portion of the entire

database


21/23

IT for Management

Prof. Efraim Turban

T3-21

Physical vs. Logical Data View

Physical View

deals with the actual, physicalarrangement and location of data in the

direct access storage devices (DASD)

Logical View

represents data in a format that is

meaningful to a user and to the software

programs that process that data


22/23

IT for Management

Prof. Efraim Turban

T3-22

Database Management

Database Design

Database Implementation

Database Administrators

responsible for ensuring that the

database fulfills that users business

needs, in terms of functionality s

well for the data itself


23/23

Copyright 2001 John Wiley & Sons, Incorporated. All

rights reserved. Reproduction or translation of this workbeyond that permitted in Section 117 of the 1976 United

States Copyright Act without the express written

permission of the copyright owner in unlawful. Request

for further information should be addressed to the

Permissions Department, John Wiley & Son, Inc.Adopters of the textbook are granted permission to make

back-up copies for his/her own use only, to make copies

for distribution to student of the course the textbook is

used in, and to modify this material to best suit their

instructional needs. Under no circumstances can copies

be made for resale. The publisher assumes no

responsibility for errors, omissions, or damages, caused

by the use of these programs or from the use of the

information contained herein.

IT for Management

Prof. Efraim Turban

6-23

Documents

data & database