Al-Bahra bin Ladjamuddin.B POSTGRADUATE PROGRAM (MTI) - STMIK RAHARJA Chapter-1

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

Introduction Database Terminology Purpose of Database Systems Database Languages Relational Databases Database Design Data Models Database Internals Database Users and Administrators Overall Structure History of Database Systems POSTGRADUATE PROGRAM (MTI) - STMIK Raharja

INTRODUCTION What a Database System Models of Reality Why use Models? A Map Is a Model of Reality A Message to Map Makers When to Use a DBMS? Data Modeling Process Modeling Database Design Abstraction

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

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

Models of Reality REALITY structures processes DATABASE SYSTEM DATABASE DML DDL l A database is a model of structures of reality l The use of a database reflect processes of reality l A database system is a software system which supports the definition and use of a database l DDL: Data Definition Language l DML: Data Manipulation Language

Why Use Models? Models can be useful when we want to examine or manage part of the real world The costs of using a model are often considerably lower than the costs of using or experimenting with the real world itself Examples: airplane simulator nuclear power plant simulator flood warning system model of US economy model of a heat reservoir map

A Map Is a Model of Reality

A Message to Map Makers A model is a means of communication Users of a model must have a certain amount of knowledge in common A model on emphasized selected aspects A model is described in some language A model can be erroneous A 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 important persistent storage of data centralized control of data control of redundancy control of consistency and integrity multiple user support sharing of data data documentation data independence control of access and security backup 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

Data Modeling REALITY structures processes DATABASE SYSTEM MODEL data modeling l The model represents a perception of structures of reality l The data modeling process is to fix a perception of structures of reality and represent this perception l In the data modeling process we select aspects and we abstract

Process Modeling REALITY structures processes DATABASE SYSTEM MODEL process modeling l The use of the model reflects processes of reality l Processes may be represented by programs with embedded database queries and updates l Processes may be represented by ad-hoc database queries and updates at run-time DML PROG

Database Design is a model of structures of reality supports queries and updates modeling processes of reality runs efficiently The purpose of database design is to create a database which

Abstraction Classification Aggregation Generalization It is very important that the language used for data representation supports abstraction We will discuss three kinds of abstraction:

Classification 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

Aggregation 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

Generalization In a generalization we form a new concept by emphasizing common aspects of existing concepts, leaving out special aspects CUSTOMER ECONOMY CLASS BUSINESS CLASS 1 ST CLASS

Generalization (cont.) CUSTOMER BUSINESS CLASS 1 ST CLASS Subclasses may overlap Subclasses may have multiple superclasses MOTORIZED VEHICLES AIRBORNE VEHICLES TRUCKSHELICOPTERSGLIDERS

Relationships Between Abstractions TTT O OO aggregationgeneralization classification AbstractionConcretization classificationexemplification aggregationdecomposition generalizationspecialization intension extension