Database Chapter 01

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CHAPTER 1:INTRODUCTION

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Database Application Development

SSK 3408


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Learning Objectives2

Define the following key terms:

Data, database and Database Management

System (DBMS), metadata.

Describe the advantages of using databaseapproach

Describe components of database

environment Briefly describe the evolution of database

systems.


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Introduction3

Over the past two decades, there has beenenormous growth in the number and theimportance of database applications.

To store, manipulate and retrieve data in nearlyevery type of organizationbusiness, healthcare, education, government and libraries.

Database technology can be used by anindividual up to large number of users accessing

databases. The knowledge derived from databases can be

used:

Competitive advantage

Customer support


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Introduction ..cont.4

DataBase Management System (DBMS) isone of the most powerful tools that can beused in building business databaseapplication.

Provide many features that representsignificant advantages over traditionalprogramming methods.

Understand the concepts of database design,queries and application building will reducethe time for developing complex applications


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Build a Business Application5

Tools:

Database Design

SQL (queries)

Programming

Design

SQL

Program

Design

SQL

Program

Best:

Spend your timeon design and SQL.

Worst:

Compensate for poor design

and limited SQL with programming.


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Basic Concepts and Definitions

Database:

A collection of data stored in a standardized format, designed to beshared by multiple users.

It may be of any size and complexity.

Data: Stored representation of objects and events that have meaning and

importance in the users environment.

Structured data or Unstructured/Multimedia data

Information:

Data that have been processed in such a way as to increase knowledgeof the person who uses the data.

Databases today may contain either data or information.

Metadata:

Data that describes the properties and context of user data

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Example of Data7


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Figure 1-1a Converting Data into Information

Context helps users understand data


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Graphical displays turn data into usefulinformation that managers can use for

decision making and interpretation


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Drawbacks of File Processing

Systems11

Program-Data Dependence

Duplication of Data

Inconsistent data

Limited data sharing

Lengthy development times

Excessive program maintenance


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Program-data Dependency12


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Problems with Data

Dependency File description are stored within each application

program that access a given file.

Consequently, any changes to a file structure requireschanges to the file description for all programs that

access to the file. It is often difficult to locate all programs affected by

such changes and consequently errors are oftenintroduced when making such changes.

Each application program must have its ownprocessing routines for reading, inserting, updatingand deleting data.

Lack of coordination and central control.

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Duplicate

Data


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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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Example of File Method

Add to file (e.g. Cell phone)

Write code to copy employeefile and add empty cell phoneslot.

Find all programs that useemployee file.

Modify file definitions.

Modify reports (as needed)

Recompile, fix new bugs.

Easier: Keep two employee

files?

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File Division

01 Employees

02 ID

02 Name

02 Address

01 Department

02 ID

02 . . .

COBOL

112 Davy Jones 999 Elm Street . . .

113 Peter Smith 101 Oak St . ..

Employee File

More programs

File Division

01 Employees

...

02 Cell Phone


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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. Therefore, requires a database management

system (DBMS)

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Order Filing

System

Invoicing

System

Payroll

System

DBMSCentral database

Contains employee,

order, inventory,

pricing, and

customer data


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DBMS

A software system that is used to create, maintain, and

provide controlled access to user databases.

It provides systematic method of creating, updating,

storing, and retrieving data in a database.

It enables end users and application programmers to

share data and it enables data to be shared among

multiple application rather than propagated and stored in

new files for every new application.

It also provides facilities for controlling data access,

enforcing data integrity, managing concurrency control,

and restoring a database.

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DBMS20

It provides interface between the various database applications for organizational

users and database

It allows users to share data and to query, access and update the stored data.


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One customer may place

many orders, but each

order is placed by a

single customer

One-to-many

relationship


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One order has many order

lines; each order line is

associated with a single order

One-to-many relationship


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One product can be in many

order lines, each order line

refers to a single product

One-to-many relationship


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Therefore, one order involves

many products and one product

is involved in many orders

Many-to-many relationship


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Relationships established in special columns that provide links between tables


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Client/server

system

architecture


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Application program functions:

insertingnew data,

updatingexisting data,

deletingexisting data,

readingdata for display

Th R f D t b


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The Range of Database

Applications30


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Pearson Education Limited, 2004

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Two-Tier Client-Server

Client manages main business and dataprocessing logic and user interface.

Server manages and controls access todatabase.


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Two-Tier Client-Server


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Three-Tier C-S Architecture

User interface layer runs on client.

Business logic and data processing layer

middle tier runs on a server (applicationserver).

DBMS stores data required by the middletier. This tier may be on a separate server(database server).


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Three-Tier C-S Architecture

A E l f P l


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An Example of Personal

Database35

A E l f W k


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An Example of Workgroup

Database36

A E l f E i D


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An Example of Enterprise Data

Warehouse37


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Advantages of Database Approach38

Program-data independence

Data-description are stored in repository not

inside the application program

Minimal data redundancy

Database design goal to integrate data files

into a single, logical structure.

Improved data consistency

By eliminating redundancy, reduce the

opportunities for inconsistencies.

Improved data sharing

A database is designed to shared corporate

resource. Authorized internal and external

users are granted permission to use the

database.

Increased productivity of application

development

New development without worry the file

design

DBMS provides high level productivity tools

Enforcement of standards

Such as naming convention, data

quality standard and uniform

procedures for accessing,

updating and protecting data

Improved data quality

Through Integrity constraint

Improved data accessibility and

responsiveness

Without the knowledge of

programming experience can

retrieve and display data, even it

crosses departmental boundaries. Reduce program maintenance

C t d Ri k f D t b


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Costs and Risks of Database

Approach39

C t f D t b


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CASE Toolscomputer-aided software engineering

Repositorycentralized storehouse of metadata

Database Management System (DBMS)software formanaging the database

Databasestorehouse of the data

Application Programssoftware using the data

User Interfacelanguages, menus, and other facilities bywhich users interact with various system components such as

CASE tools, DBMS etc. Data/Database Administratorspersonnel responsible for

maintaining the database

System Developerspersonnel responsible for designingdatabases and software

End Userspeople who use the applications and databases

Components of Database

Environment40

C t f D t b


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Components of Database

Environment41

Hardware

PC, Mainframe, Networkcomputer

Software

Programming Language Data

Procedures

Instructions and rules

People

Data and Database

Administrator, SystemDeveloper, End-user

Database Management


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Database Management

Approach

Data is most important

Data defined first

Standard format

Access through DBMS

Queries, Reports, Forms

Application Programs

3GL Interface

Data independence

Change data definition without changing

code

Alter code without changing data

Move/split data without changing code

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All Data

DBMS

Program1 Program2Queries

Reports


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Modifying Data with DBMS

Add cell number to

employee table

Open table definition

Add data element

If desired, modify reports

Use report writer

No programming

Existing reports, queries,

code will all run as beforewith no changes.

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Field Name Data Type Description

EmployeeID Number Autonumber..

TaxpayerID Text Federal ID

LastName Text

FirstName Text. . .

Phone Text

. . .

CellPhone Text Cellular . . .


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DBMS Features/Components

Database engine

Storage, retrieval,

update

Enforce businessrules

Performance and

ability to handlelarge problems

Data dictionary

Query Processor

Utilities

Security

Report writer

Forms generator

(input screens)

Applicationgenerator

Communications

3GL Interface

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DBMS Components45

All Data

Database EngineData Dictionary

Security

Query Processor

FormBuilder

ReportWriter

Communication

Network

3GL

Connector

Program

Application

Generator


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DBMS Engine, Security, Utilities46

Data

Tables

ProductItemID Description

887 Dog food

946 Cat food

OrderOrderID ODate

9874 3-3-97

9888 3-9-97

CustomerCustomerID Name

1195 Jones

2355 Rojas

User Identification

Access RightsSecurity

Concurrency and

Lock Manager

UtilitiesBackup and

Recovery

Administration

Database

EngineProduct

ItemID Integer, Unique

Description Text, 100 char

Customer

CustomerID Integer, Unique

Name Text, 50 char Data

Dictionary


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DBMS Query Processor47

All Data

Database Engine

Data Dictionary

Query Processor


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Report Writer (Oracle)49


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DBMS Input Form50

All Data

Database Engine

Data Dictionary

Query Processor

Form Builder

Input

Form

Design


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Example of Commercial DBMS51

Oracle

Ingres

Informix (Unix) DB2, SQL/DS (IBM)

Access (Microsoft)

SQL Server (Microsoft +)

Many older (Focus, IMS, ...)

Many limited PC (dBASE, Paradox, )


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Significance of using DBMS52

Applications change a lot, but same data.

Need for ad hocquestions and queries.

Need to reduce development times. Need shared data.

Improve quality of data.

Enable users to do more development.


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Flat files - 1960s - 1980s

Hierarchical1970s - 1990s

Network1970s - 1990s

Relational1980s - present

Object-oriented1990s - present

Object-relational1990s - present

Data warehousing1980s -present

Web-enabled1990s - present

Evolution of Database Systems53


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Customers

Orders

Item Description Quantity

998 Dog Food 12

764 Cat Food 11

Items

Customer

Order

Items Ordered

To retrieve data, you

must start at the top

(customer). When you

retrieve a customer, you

retrieve all nested data.

Hierarchical Database


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Customer

OrderItems

Ordered

Items

Entry point

Entry point

Network Database


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Customer(CustomerID, Name,

Order(OrderID, CustomerID, OrderDate,

ItemsOrdered(OrderID, ItemID, Quantity,

Items(ItemID, Description, Price,

Data is stored in separate sets of data

The tables are not physically connected.

Instead, data is linked between column

Ex: retrieve order, database can match customer and order

by customerID

Relational Database


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CustomerCustomerID

Name

Add CustomerDrop Customer

Change Address

OrderOrderID

CustomerID

NewOrderDeleteOrder

OrderItem

OrderIDItemID

OrderItem

DropOrderItem

Item

ItemIDDescription

New Item

Sell Item

Buy Item

Government

CustomerContactName

ContactPhoneDiscount,

NewContact

Commercial

Customer

ContactNameContactPhone

NewContact

Object3 component

- name

- a set of properties or attributes

- a set of methods or functions

Object-Oriented Database


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Reference:

Hoffer, J.A, Ramesh, V., Topi, H. 2011. Modern

Database Management. 10thEdition, Pearson

Education Limited.

Post, G.V. 2005. Database ManagementSystems: Designing and Building Business

Application, 3rdEdition, McGraw Hill.

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Summary59

In this chapter you learned how to:

Define the following key terms:

Data, database, Information, Metadata and Database

Management System (DBMS).

Describe the advantages of using database

approach

Describe components of database environment

Briefly describe the evolution of databasesystems.

Database Chapter 01

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