Handout TIF201 Ch 1 Pendahuluan

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Chapter 1 Part One: Introduction to Database |1-1 1

Database Systems:

Thomas Connolly, Carolyn Begg, Database System, A Practical Approach to Design Implementation and Management, 4thEdition, Addison Wesley

Chapter 1 Part One: Introduction to Database | 2

Learning Outcomes

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Introduction

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Traditional File-based Systems

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Database Approach

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Roles in the Database Environment

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Advantages & Disadvantages of DBMS

Chapter 1 Part One: Introduction to Database | 3 DBMS

Introduction

Database

Database System

Database Apps.

Examples of Database Application

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Purchases from the supermarket

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Purchases using credit card

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Booking a holiday at the travel

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Using the local library

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Taking out insurance

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Using the Internet

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File-based Approach

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Traditional file-based system

–An early file-based system (tradditionl way) use the manual filing system

– A “mistake” database system –We can learn from that mistake

•Prefevent from reapeating the problem that coused by this mistake

•Understanding how the file system works

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Collection of application program that perform services for the

end users (e.g reports)

• Program defines and manages it’s own data

File-based Processing

Limitations of File-based

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Separation and isolation

–When data is isolated in separate files, it is more difficult to access data that should be available.

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Duplication

–Uncontrolled duplication of data accour

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Program and data dependence

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Limitations of File-based

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Incompatible file format

–Because the structure of files is embedded in the application programs, the structures are dependent on the application programming language.

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Fixed queries and proliferation of application programs

–The requirement for new or modified queries grew

Database

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Limitation of file-based factors:

–(1) the definition of the data is embedded in the application programs, rather than being stored separately and independently;

–(2) there is no control over the access and manipulation of data beyond that imposed by the application programs.

Database

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Definition

–A shared collection of logically related data, and a description of this data, designed to meet the information needs of an organization.

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Logical Related

–When we analyze the information needs of an organization, we attempt to identify

entities, attributes, and relationships.

•Entities: is a distinct object (a person, place, thing, concept, or event) in the organization that is to be represented in the database

•Attributes: is a property that describes some aspect of the object that we wish to record.

•Relationship: is an association between entities.

Database

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Database characteristics

–A large repository of data that can be used simultaneously by many departments and users.

–All data items are integrated with a minimum amount of duplication.

–Shared resource.

–Holds not only the organization’s operational data but also a description of this data (a self-describing and integrated data files)

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System catalog

–Metadata

–Data dictionary

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Database

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Program-data independencies

–The nature of database

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Data abstraction

–One advantage of this approach, is that we can change the internal definition of an object without affecting the users of the object, provided the external definition remains the same.

Database Management System (DBMS)

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A software system that enables users to define, create, maintain,

and control access to the database.

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Facilities:

–Data definition language (DDL) - allows users to specify the data types and

structures and the constraints on the data to be stored in the database.

–Data manipulation language (DML)/query language - allows users to insert,

update, delete, and retrieve data from the database.

–Structured query language (SQL)–standard language for DBMS.

–Security system - which prevents unauthorized users accessing the database.

–Integrity system - which maintains the consistency of stored data.

–Concurrency control system - which allows shared access of the database.

Database Approach as DBMS

–Recovery control system - which restores the database to a previous consistent

state following a hardware or software failure.

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DBMS Environment

• Hardware

–Client-server architecture

• Software

–dbms, os, network, application

• Data

–Schema, subschema, table, attribute

• People

–Data administrator & database administrator

–Database designer: logical & physical

–Application programmer

–End-user: naive & sophisticated

DBMS Environment

• Procedure

–Start, stop, log on, log off, back up, recovery

Roles in the Database Environment

• Data Administrator (DA) –Management of data resources

–Ensure database development support corporate objectives • Database Administrator (DBA)

–Physical realization of database –More technically oriented • Database Designers

–Logical •Identifying data –Physical

•Realization of logical database • Application Programmers

–Implement application program for user • End Users (Naïve and Sophisticated)

Advantages of DBMS

• Control redundancy

• Consistency

• Integrity

• Security

• Concurrency control

• Backup & recovery

• Data standard

• More information

• Data sharing & conflict control

• Productivity & accessibility

• Economy of scale

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Limitations of DBMS

• Complexity • Size • Cost

–Software

–Hardware

–Conversion

• Performance • Vulnerability