files and databases

5/21/2018 FILES and DATABASES

1/57

1 File Systems and DatabasesChapter 1 The Worlds

of Database Systems

Prof. Sin-Min Lee

Dept. of Computer Science


2/57

1

Tuesday Thursday

10:15 11:30


3/57

1

??!

Your evaluation in this course is determined by:

30%

Class Presentation 10%

Presentation report 5%


4/57

1


5/57

1


6/57

1

Text Book

NARAYAN S.UMANATH &

RICHARD W.

SCAMELL, DATA

MODELING AND

DATABASE

DESIGN, 2007Thomson


7/57

1

A. Silberschatz, H.F. Korth, S. Sudarshan: Database System

Concepts, 5th Ed., McGraw-Hill, 2006.

GOOD REFERENCE


8/57

1

The mediocre teacher tells.The good teacher explains.

The superior teacher

demonstrates.

The great teacher inspires.


9/57

1

Files and Databases

File: A collection of records or documents dealingwith one organization, person, area or subject

(Rowley)

Manual (paper) files

Computer files

Database: A collection of similar records withrelationships between the records (Rowley)

Bibliographic, statistical, business data, images, etc.


10/57

1

Introducing the Database

Major Database Concepts

Data and information

Data - Raw facts

Information - Processed data

Data management

Database

Metadata

Database management system (DBMS)


11/57

1


12/57

1


13/57

1

Figure 1.1

Sales per Employee for Each of ROBCORS Two Divisions


14/57

1


15/57

1

Database Systems Types of Database Systems

Number of Users

Single-user

Desktop database

Multiuser

Workgroup database

Enterprise database

Scope

Desktop

Workgroup

Enterprise


16/57

1

Database Systems Types of Database Systems

Location

Centralized

Distributed

Use

Transactional (Production)

Decision support

Data warehouse


17/57

1

Database

A Database is a collection of stored operational dataused by the application systems of some particular

enterprise (C.J. Date)

Paper Databases

Still contain a large portion of the worlds knowledge

File-Based Data Processing Systems

Early batch processing of (primarily) business data

Database Management Systems (DBMS)


18/57

1

Why DBMS?

History

50s and 60s all applications were custom built for particular

needs

File based

Many similar/duplicative applications dealing withcollections 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


19/57

1

File Based Systems

Naughty

NiceJust whatasked for

Coal

Estimation

Delivery

List

Application File

ToysAddresses

Toys


20/57

1

From File Systems to DBMS

Problems with file processing systems

Inconsistent data

Inflexibility

Limited data sharing

Poor enforcement of standards

Excessive program maintenance


21/57

1

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


22/57

1

Terms and Concepts

Data independence

Physical representation and location of data and the use of

that data are separated

The application doesnt 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


23/57

1

Database Environment

CASE

Tools

DBMS

User

Interface

Application

Programs

Repository Database


24/57

1

Database Components

DBMS===============

Design toolsTable Creation

Form Creation

Query CreationReport Creation

Procedural

language

compiler (4GL)

=============

Run time

Form processorQuery processor

Report Writer

Language Run time

UserInterface

Applications

Application

ProgramsDatabase

Database contains:

Users Data

Metadata

Indexes

Application Metadata


25/57

1

Types of Database Systems

PC databases

Centralized database

Client/server databases

Distributed databases Database models


26/57

1

PC Databases

E.g.:

Access

FoxPro

DbaseEtc.


27/57

1

Centralized Databases

Central

Computer


28/57

1

Client Server Databases

NetworkClient

Client

Client

DatabaseServer


29/57

1

Distributed Databases

computercomputer

computer

Location A

Location CLocation B

HomogeneousDatabases


30/57

1

Distributed Databases

Local Network

DatabaseServer

Client

Client

CommServer

Remote

Comp.

Remote

Comp.

Heterogeneous

Or Federated

Databases


31/57

1


32/57

1


33/57

1


34/57

1


Importance of DBMS

It helps make data management more efficient

and effective.

Its query language allows quick answers to ad

hocqueries.

It provides end users better access to more and

better-managed data.

It promotes an integrated view of organizationsoperations -- big picture.

It reduces the probability of inconsistent data.


35/57

1


36/57

1

Figure 1.2

The DBMS Manages the Interaction

Between the End User and the Database


37/57

1


38/57

1


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.


39/57

1


40/57

1


41/57

1


42/57

1


43/57

1

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.


44/57

1

Figure 1.3

Contents of the CUSTOMER File


45/57

1


46/57

1


47/57

1

Table 1.1 Basic File TerminologyData Raw facts that have little meaning unless they have been

organized in some logical manner. The smallest piece of datathat can be recognized by the computer is a singlecharacter, such as the letter A, the number 5, or somesymbol such as; ? > * +. A single character requires onebyte of computer storage.

Field A character or group of characters (alphabetic or numeric)that has a specific meaning. A field might define a telephonenumbers, a birth date, a customer name, a year-to-date(YTD) sales value, and so on.

Record A logically connected set of one or more fields that describesa person, place, or thing. For example, the fields thatcomprise a record for a customer named J. D. Rudd mightconsist of J. D. Rudds name, address, phone number, dateof birth, credit limit, unpaid balance, and so on.

File A collection of related records. For example, a file mightcontain data about ROBCOR Companys vendors; or, a filemight contain the records for the students currently enrolledat Gigantic University.


48/57

1Figure 1.4

Contents of the AGENT File


49/57

1

A Simple File System

Figure 1.5


50/57

1


51/57

1


52/57

1


53/57

1


54/57

1


55/57

1


56/57

1


57/57

1

files and databases

Documents

databases file

2007thomson5212018 files

divisions5212018 files

computer science5212018

good reference5212018

date paper databases

file systems

database systemconcepts