Chapter 1 The Worlds of Database Systems File Systems and Databases Prof. Sin-Min Lee Dept. of Computer Science

Tuesday Thursday 10:15 – 11:30

Your evaluation in this course is determined by: 30% Class Presentation 10% Presentation report 5% ??!

Text Book NARAYAN S. UMANATH & RICHARD W. SCAMELL, DATA MODELING AND DATABASE DESIGN, 2007 Thomson

GOOD REFERENCE A. Silberschatz, H.F. Korth, S. Sudarshan: Database System Concepts, 5th Ed., McGraw-Hill, 2006.

William Arthur Ward The mediocre teacher tells. The good teacher explains. The superior teacher demonstrates. The great teacher inspires. William Arthur Ward

Files and Databases File: A collection of records or documents dealing with one organization, person, area or subject (Rowley) Manual (paper) files Computer files Database: A collection of similar records with relationships between the records (Rowley) Bibliographic, statistical, business data, images, etc.

Introducing the Database Major Database Concepts Data and information Data - Raw facts Information - Processed data Data management Database Metadata Database management system (DBMS)

Sales per Employee for Each of ROBCOR’S Two Divisions Figure 1.1

Database Systems Types of Database Systems Number of Users Scope Single-user Desktop database Multiuser Workgroup database Enterprise database Scope Desktop Workgroup Enterprise

Database Systems Types of Database Systems Location Use Centralized Distributed Use Transactional (Production) Decision support Data warehouse

Database A Database is a collection of stored operational data used by the application systems of some particular enterprise (C.J. Date) Paper “Databases” Still contain a large portion of the world’s knowledge File-Based Data Processing Systems Early batch processing of (primarily) business data Database Management Systems (DBMS)

Why DBMS? History 50’s and 60’s all applications were custom built for particular needs File based Many similar/duplicative applications dealing with collections of business data Early DBMS were extensions of programming languages 1970 - E.F. Codd and the Relational Model 1979 - Ashton-Tate and first Microcomputer DBMS

File Based Systems File Application Nice Toys Delivery Addresses List Naughty Coal Estimation Toys Nice Just what asked for

From File Systems to DBMS Problems with file processing systems Inconsistent data Inflexibility Limited data sharing Poor enforcement of standards Excessive program maintenance

DBMS Benefits Minimal data redundancy Consistency of data Integration of data Sharing of data Ease of application development Uniform security, privacy, and integrity controls Data accessibility and responsiveness Data independence Reduced program maintenance

Terms and Concepts Data independence Physical representation and location of data and the use of that data are separated The application doesn’t need to know how or where the database has stored the data, but just how to ask for it Moving a database from one DBMS to another should not have a material effect on application program Recoding, adding fields, etc. in the database should not affect applications

Database Environment CASE Tools DBMS User Interface Application Programs Repository Database

Database Components DBMS Application Programs Design tools Database =============== Design tools Table Creation Form Creation Query Creation Report Creation Procedural language compiler (4GL) ============= Run time Form processor Query processor Report Writer Language Run time User Interface Applications Application Programs Database Database contains: User’s Data Metadata Indexes Application Metadata

Types of Database Systems PC databases Centralized database Client/server databases Distributed databases Database models

PC Databases E.g.: Access FoxPro Dbase Etc.

Centralized Databases Computer

Client Server Databases Network Client Database Server

Distributed Databases Location B Location C computer computer Homogeneous Databases computer Location A

Distributed Databases Client Heterogeneous Or Federated Databases Remote Comp. Local Network Database Server Comm Server Remote Comp. Client

Introducing the Database Importance of DBMS It helps make data management more efficient and effective. Its query language allows quick answers to ad hoc queries. It provides end users better access to more and better-managed data. It promotes an integrated view of organization’s operations -- “big picture.” It reduces the probability of inconsistent data.

Figure 1.2 The DBMS Manages the Interaction Between the End User and the Database Figure 1.2

Introducing the Database Why Database Design Is Important? A well-designed database facilitates data management and becomes a valuable information generator. A poorly designed database is a breeding ground for uncontrolled data redundancies. A poorly designed database generates errors that lead to bad decisions.

Historical Roots Why Study File Systems? It provides historical perspective. It teaches lessons to avoid pitfalls of data management. Its simple characteristics facilitate understanding of the design complexity of a database. It provides useful knowledge for converting a file system to a database system.

Contents of the CUSTOMER File Figure 1.3

Table 1.1 Basic File Terminology

Contents of the AGENT File Figure 1.4

A Simple File System Figure 1.5