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POSTGRADUATE PROGRAM (MTI) - STMIK RAHARJA

Chapter-1Chapter-1

POSTGRADUATE PROGRAM (MTI) - STMIK RAHARJA

• Elmasri, Navathe, “Fundamental of DATABASE SYSTEMS”, 4th edition, Addison Wesley Publishing, 2004.

• Thomas Connoly, Carolyn Begg, ”DATABASE SYSTEMS A Practical Approach to Design,Implementation, and Management”, 4th edition, Addison Wesley Publishing, 2004.

IntroductionDatabase TerminologyPurpose of Database SystemsDatabase LanguagesRelational DatabasesDatabase DesignData ModelsDatabase InternalsDatabase Users and AdministratorsOverall StructureHistory of Database Systems

POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

INTRODUCTIONWhat a Database System Models of RealityWhy use Models?A Map Is a Model of RealityA Message to Map MakersWhen to Use a DBMS?Data ModelingProcess ModelingDatabase DesignAbstraction

POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

o System In data Processing, a collection of men, machines, and methods organized to accomplish a set of specific functions.

o Computer system A computer together with all the device and programs that are necessary for its operations.

o Data the description of things and events that we face.

o Business data an organization’s description of things (resources) and events (transactions) that it face

o Data, in turn defined as recorded facts or figures..

SYSTEM, DATA, INFORMATIOAN

POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

o Information knowledge derived from data.

o Information data placed within a context. Information the amount of uncertainty that is reduced when a massage is received.

o Information a difference that makes a difference.

A Database is a collection of related Data. By data, we mean known facts that can be recorded and that have implicit meaning. For Example, consider tne names, telephone numbers, and addres (general deifinition).

A Database represents some aspect of the real world, sometimes called the miniworld or the universe of discourse (UoD), Changes to the miniworld are reflected in the database.

A Database is logically coherent collection of data with some inherent meaning.

A Database is designed, built, and populated with data for spesific purpose. It has an intended group of users and some preconceived applications in which these users are interested.

POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

DATABASE

New Aplication of database systems, such : Multimedia databases, can now store pictures, video

clips, and sound messages. GIS can store and analyze maps, weather data, and

satellite images. Data warehouses and online analytical processing

(OLAP) systems are used in many companies to extract and analyze useful information from very large databases for decision making.

Realtime and active database technology is used in controlling industrial and manufacturing processes

POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

DBMSThe Software which handles all access to the database. A collection of programs that enables users to create and maintain a database

REALITY

• structures

• processes

DATABASE SYSTEM

DATABASE

DML

DDL

A database is a model of structures of reality The use of a database reflect processes of reality A database system is a software system which supports the

definition and use of a database DDL: Data Definition Language DML: Data Manipulation Language

Why Use Models?Models can be useful when we want to examine

or manage part of the real worldThe costs of using a model are often

considerably lower than the costs of using or experimenting with the real world itself

Examples:airplane simulatornuclear power plant simulatorflood warning systemmodel of US economymodel of a heat reservoirmap

A Message to Map MakersA model is a means of communicationUsers of a model must have a certain amount of

knowledge in commonA model on emphasized selected aspectsA model is described in some languageA model can be erroneousA message to map makers: “Highways are not

painted red, rivers don’t have county lines running down the middle, and you can’t see contour lines on a mountain” [Kent 78]

Use a DBMS when this is importantpersistent storage of data centralized control of datacontrol of redundancycontrol of consistency and

integritymultiple user supportsharing of datadata documentationdata independencecontrol of access and

securitybackup and recovery

Do not use a DBMS when the initial investment in

hardware, software, and training is too high

the generality a DBMS provides is not needed

the overhead for security, concurrency control, and recovery is too high

data and applications are simple and stable

real-time requirements cannot be met by it

multiple user access is not needed

REALITY

• structures• processes

DATABASE SYSTEM

MODEL

data modeling

The model represents a perception of structures of reality

The data modeling process is to fix a perception of structures of reality and represent this perception

In the data modeling process we select aspects and we abstract

REALITY

• structures• processes

DATABASE SYSTEM

MODEL

process modeling

The use of the model reflects processes of reality Processes may be represented by programs with

embedded database queries and updates Processes may be represented by ad-hoc database

queries and updates at run-timeDML DML

PROG

Database Design

is a model of structures of realitysupports queries and updates modeling

processes of realityruns efficiently

The purpose of database design is to create a database which

Abstraction

ClassificationAggregationGeneralization

It is very important that the language used for data representation supports abstraction

We will discuss three kinds of abstraction:

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.

CUSTOMER

Tom Ed Nick ... Liz Joe Louise

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

AIRPLANE

COCKPIT

ENGINE

WING

In a generalization we form a new concept by emphasizing common aspects of existing concepts, leaving out special aspects

CUSTOMER

ECONOMYCLASS

BUSINESS

CLASS1STCLASS

CUSTOMER

BUSINESSCLASS

1STCLASS

Subclasses may overlap

Subclasses may have multiple superclasses

MOTORIZED VEHICLES

AIRBORNE VEHICLES

TRUCKS HELICOPTERS GLIDERS

T TT

OO O

aggregation generalization

clas

sific

atio

nAbstraction Concretization classification exemplification aggregation decomposition generalization specialization

intension

extension