Introduction To Database System

Welcome to BITP 1323

SEMESTER 2/2014/201523 February - 4 June 2015

DATABASE LECTURE

DITP 1333

AGENDA: WEEK 1

Database Introduction

• Introduction to Data & Information

• Traditional File-Base System vs Database Approach

• Roles in DB Environment• DBMS History• DBMS Advantages & Disadvantages

Database Environment

• ANSI-SPARC Architecture• Data Model and Conceptual Modeling

• Functions of DBMS

Database Introduction

Traditional File Based System

vs Database Approach

Roles in DB

Environment

DBMS

History

DBMS Advantages & Disadvantages

• Database concept has been widely used in large or small organization.

• This concept arises from the need to build a lot of data processing systems.

• Organization store data about their daily activities and their interaction between external environments.

Introduction

UNIVERSITY

TOUR AGENT

CLINIC

•Digital data are stored in computers as files. Often, data are arrayed in tabular form. For this reason, data files are often

called tables. •A database is a collection of tables. •Businesses and government agencies that serve large clienteles, such as telecommunications companies, airlines, credit card firms, and banks, rely on extensive databases for their billing, payroll, inventory, and marketing operations.

•Database management systems are information systems that people use to store, update, and analyze non-geographic databases.

IntroductionDatabase Introductio

n Digital Data

information

data

UNIVERSITY TOUR AGENT CLINIC

EmployeesStudentsCourses

EmployeesHoliday Packages

Booking

EmployeesMedicinePatients

nameaddress

staff number

Package namePackage price

nameaddressallergies


n Information vs Data

Information can be defined as data that has been processed and are useful

Data referred to as the facts of any object or event to be stored in computer media.

Groceries 499 400 99

School 200 0 200

Medical 900 35 865

For example the list below will be useless because we do not know what the purpose of the data collected. Assumptions can be made to the existing data, but it does not make the information we have is accurate and relevant.

(a) Data in context (b) Summarized data

By adding text and applying some appropriate structure (Figure 2) to the data, it will change the way we interpret the collected data.


n Convert data into Information

UNIVERSITY Environment

STUDENT File

Name Address Age Faculty Department

1 Mariam Perak 23 FTMK SE

2 Zulaikha Johor 24 FTMK MM

3 Zaki Selangor 22 FTMK SE

4 Aliff Terengganu 23 FTMK SE

Attribute Name

Attribute Value

Record

Real World

Entity

File-based System is a Collection of application programs that

perform services for the end-user such as the production of reports. Each

program defines and manages its own data.

Traditional File-based System Database Introductio

n vs Database Approach

• Before the database system is introduced, the data is stored in a separate file and stored on magnetic tape or diskette.

• Each data processing applications have their own input and output for the application executable

Student FileStudent application

program

Course application program

Finance application program

student name, student address,

matrices number

Course File

course name, course code,

Finance File

customer number,

customer name


n

File-based system approach

FILE-BASED SYSTEM

Applications developed in an ad-hoc

Data requirements for applications derived independently

Data files developed for individual applications

Application programs are data dependent

Centralization of information management

Data shared by different groups of users and application programs

Provision of multiple interfaces

Representation of complex relationships between data

Integrity constraint handling

Advanced facilities for backup and recovery

DATABASE APPROACH SYSTEM


n vs Database Approach

Limitation

INCOMPATIB

LE FILE

FORMATS

DATA DEPENDEN

CE

SEPARATION OF DATA

REDUNDANCYDUPLICATION OF DATAFIXED

QUERIS OF

APPLICATION

PROGRAMS

of file-based systems

Database Introductio

n

Database is a shared collection of logically related data, and a description of this data, designed to meet

the information needs of an organisation.

database is a large repository of data

can be accessed simultaneously by

department and users

holds organization’s operational data and description of data

(catalog)

holds data data that is logically related.

(relationships between entities)

DatabaseDatabase Introductio

n

Name Address Age Faculty Enroll Date

1 Mariam Perak 23 FTMK 1/9/2014

2 Zulaikha Johor 24 FTMK 1/9/2014

3 Zaki Selangor 22 FTMK 1/9/2014

4 Aliff Terengganu 23 FTMK 1/9/2014

User Data is stored in a table.Example: STUDENT TABLE

Metadata is “data about data”Example: Metadata for STUDENT TABLE

Field Name Data Type Size

Name VARCHAR 23

Address VARCHAR 24

Age NUMBER 22

Faculty VARCHAR 23

Enroll Date DATE 8

Matric No Name Address Age Enroll Date

1 D123 Mariam Perak 23 1/9/2014

2 D213 Zulaikha Johor 24 1/9/2014

3 D312 Zaki Selangor 22 1/9/2014

4 D411 Aliff Terengganu 23 1/9/2014

INDEX is used for faster data retrieval.Example: Indexing using matric number

Metadata Application : keep the structure and format of reports, queries, forms and other applications.

Database Database Introductio

n

Components

ROLES in Db environment


n

supervises

END USERS PROGRAMMERS

SYSTEM ADMINISTRATO

R

DATABASE ADMINISTRATO

R

DB DESIGNER

application programs

procedures and standards

use write

ANALYST

writes and enforces

designs

manages

DBMS

DATA

DBMS utilities

hardware

access

• Collection of programs that manages database structure and controls access to data

• Possible to share data among multiple applications or users

• Makes data management more efficient and effective

DBMS DATABASE MANAGEMENT

SYSTEM


n

http://education-portal.com/academy/lesson/what-is-a-database-management-system-purpose-and-function.html

REF






Before-1950s• Data was stored as paper

records.• Lot of man power involved.• Lot of time was wasted.e.g. when

searching• Therefore inefficient.

Early manual system

1950s and early 1960s:• Data processing using magnetic

tapes for storage• Tapes provide only sequential

access• Punched cards for input

Late 1960s and 1970s:• Hard disks allow direct access to

data• Data stored in files• Known as File Processing System

Revolution began

DBMS Database Introductio

nHistory

File-based system Database Approach

• Adequate for small applications

Drawbacks• Separation and isolation of data Each program

maintains its own set of data.• Users of one program may be unaware of potentially

useful data held by other programs.

Duplication of data• Same data is held by different locations. • Wasted space and potentially different values and/or

different formats for the same item.

Data dependence• File structure is defined in the program code.

Incompatible file formats• Programs are written in different languages, and so

cannot easily access each other’s files.

Fixed Queries/Proliferation of application programs• Programs are written to satisfy particular functions.• Any new requirement needs a new program.

Arose because:• Definition of data was embedded in application

programs, rather than being stored separately and independently.

• No control over access and manipulation of data beyond that imposed by application programs.

Result:The database and Database Management

System (DBMS).


nHistory

is to overcome the shortcomings of file-oriented systems

1950 1960 1970 1980 1990

File- oriented

Hierarchical

Network

Relational

Object-Oriented

Fully integrated

Fully modular

MO

DU

LA

RIT

Y C

ON

TR

OL

TIME

was developed as a response to the limitations of hierarchical designs

emerged as a new solution to problems raised by both hierarchical and network designs


nHistory

Each new approach to database design required the use of increasingly powerful computers to achieve satisfactory performance for large volumes of data.


nHistory

• File-oriented systems preserved specific data files for specific programs. This was efficient from a processing standpoint, but soon led to complications from a business standpoint.

• File-oriented systems tended to be slow, hard to maintain, and very cumbersome when business processes required trading data across organizational functions or departments: too often the programs in one department could not read the data used by programs in another.

• moving data across functional boundaries (to track a business process, for example) was extremely difficult, if not impossible.

Example:It would be very difficult for a sales representative to tell a customer what the expected price changes on back-ordered products might be since prices reside with Accounting while inventory information resides with the Orders Department; both sets of data are accessed by different people using different systems; and the file formats used by different programs may be incompatible.

CUSTOMER MASTER FILE

INVENTORY MASTER FILE

BACKORDER FILE

INVENTORYPRICING

FILE

CUSTOMERRECEIPT FILE

ORDER SYSTEM INVOICE SYSTEM

SALES REPALI

SALES REPAMINAH

ACC STAFFCHONG

ACC STAFF AHMAD

File- oriented


n

Example:A hierarchical database is designed for rapid searches of orders by customer number. Each customer number is linked to a customer name and address and one or more orders. By searching to find what orders are associated with a customer number, sales representatives can find what products are included in any order, and search the database separately to find which orders are backordered. Accounting staff can accumulate order quantities and prices by customer number to generate invoices.

• The advantages of separating data from programs using a DBMS is shown in Figure 1.

• Now any sales rep can use the database to answer customer's questions about orders, and any member of the accounting staff can use the database to generate invoices.

• Hierarchical database begins to solve the data fragmentation problems suggested by the file-oriented design and offers a way to share data for multiple purposes across organizational boundaries.

ORDER SYSTEM

Customer Number

Name & AddressOrder(s)

product

price

ProductNumber

Backorder(s)

product

price

Hierarchical Database

INVOICING SYSTEM

(a)

(b)

Figure 1


n

For, example, an explicit pathway is maintained between product numbers, orders, and prices (see the arrow labeled (a) in Figure 2). Maintaining this link would make it easier to traverse from customer orders to backordered products to determine the intersection of the two sets .

Example:Which records exist in both groups. The result would list what customers had products on backorder, and describe pricing for those products. In this sense, the network database would make it easier to collect pricing information without the potentially cumbersome multi-step processing required by the hierarchical design.

• Evolved in part to solve navigational problems encountered in hierarchical designs.

• In practice, the two types of databases often appear quite similar.

• Network designs, however, build more sophisticated links between database records than do hierarchical approaches. In particular, network designs enable multiple paths between records.

INVOICING SYSTEMORDER

SYSTEM

explicit pathway

ProductNumber

Backorder(s)

Network Database

Customer Number

Name & Address

Order(s)

product

price product

price

(a)

Figure 2

PRODUCT TABLE

Prod #Prod_Nam

e

10 Mini Ipad

20 Iphone 6

30 laptop

Relational Database

CUSTOMER TABLE

Cust #Cust_Nam

e

100 Ali

200 Aminah

300 Ahmad PRICE TABLE

Prod #Prod_Nam

e

10 RM 1000

20 RM 2800

30 RM 3900

BACKORDER TABLE

Prod # Date

30 June 2014

ORDER TABLE

Cust # Prod #

300 20

100 30


n

• The Backorder table describes that Product 30 was backorders as of June. • The Order table identifies Customer 100 as having ordered Product 30. • The Price table lists the price of Product 30 as RM 3900. • The Product table provides the name of Product 30 and the Customer

table provides the name of Customer 100.

A manager wants to know how much revenue is represented by backordered product.

Query : Who is back-ordered and for what revenue?


n

Prod # Cust # Prod_Name Cust_Name Date Price

30 100 laptop Ali June 2014 RM 3900

RESULT


n

ALI

Address Credit limit

Melaka RM 1000

CUSTOMER

Attribute Attribute

Att Value Att Value

INHERITANCE

ADDRESS

Street Location Code

SPECIALIZATION

SG Address

MY Address

StreetZip

Code StreetPostal Code

Object-Oriented

OBJECT

Attribute Attribute

Att Value Att Value

Specialization

Inheritance

TYPES of Database


n

There are different ways to refer to databases (and DBMSs). Based on :

• number of concurrent users, • geographic location of the data, • how they will be used and on the time

sensitivity of the information gathered (example: service sales, payment, etc) .

NUMBER OF USERS

1

14

DATABASE TYPE DESCRIPTION

Single-userSupports only a single user at a time. Usually only works on a PC

DesktopSingle user database that runs on a PC also called "desktop database"

Multi-userSupports several users at the same time. Can be PC or mainframe based.

WorkgroupSmall multi-user database (usually 50 users or less)

EnterpriseLarge multi-user database. Usually runs on a mainframe.

TYPES of Database


n

1

LOCATION

✓ Supports data located at a single site ✓ Supports data distributed across several sites

TYPES of Database


n

1

16

•Transactional (or production):– Supports a company’s day-to-day operations

•Data warehouse:– Stores data used to generate information required to make tactical or

strategic decisions– Often used to store historical data– Structure is quite different

USE

TYPES of Database


n

ORACLE

MY SQL

MICROSOFT SQL SERVERMICROSOFT

ACCESS

INFORMIX

SYBASE

INGRESS

DBMS Software


n

•Database management systems are valuable because they

provide secure means of storing and updating data. •Database administrators can protect files so that only authorized

users can make changes. •DBMS provide transaction management functions that allow

multiple users to edit the database simultaneously. • In addition, DBMS also provide sophisticated means to retrieve

data that meet user specified criteria. In other words, they enable

users to select data in response to particular questions. A

question that is addressed to a database through a DBMS is

called a query.

DBMS why?


n


nAdvantages & Disadvantages

Advantages Disadvantages

1. control of redundant data can be done because the data is stored in one location

2. higher consistency of data can be done with the control of redundant data

3. More information can be generated from the same data.

4. More economical in terms of manpower, storage and cost

5. additional concurrent control 6. better security, such as the use of

passwords

1. the complexity of the development process will have an impact on system performance

2. DBMS size is quite large and involve a lot of storage

3. high costs in building a DBMS and the provision of hardware

4. high costs in the transition from traditional file system to a database system

5. impact of failure is higher because users and applications depend on DBMS


ANSI-SPARC Architecture

Data Model and Conceptual Design

Function of

DBMS

40

ANSI-SPARCARCHITECTURE


• consists of three levels.

• proposed by the Standard Planning and Requirements Comittess of the American Standards Institute Comittee on Computers and Information Processing (ANSI / SPARC).

View 1 View 2 View 3

Conceptual Level

Internal/Physical Level

mapping

mapping

DATABASE

External Level

The purpose of this architecture is to distinguish between the way the physical display of the database and describe how users view the database because:



• each user have a different view of the same data

• needs and views of the users of the data may change over time

• end-users should not interfere with the complex structure of the database storage

• changes to the logical database by the DBA should not involve all users

DBMS View

Designer’s View



CREATE TABLE CUSTOMER (cust_no varchar (12),cust_name varchar (20),cust_salary number,cust_dob date));

View 1 View 2

Conceptual Level

Internal/Physical

Level

External Level

CUSTOMER TABLE

Cust # Cust_Name Cust_Salary Cust_B.O.D

100 Ali 1000 2 JUNE 1981

CUSTOMER TABLE

Cust # Cust_Name

100 Ali

CUSTOMER TABLE

Cust #Cust_Nam

eCust_Salar

yCust_B.O.D

100 Ali 1000 2 JUNE 1981

The physical representation of the database on the computer. This level describes how the data id stored in the database. (e.g: storage space allocation , record descriptions for storage)

40

Database System Components


Database system is composed of five main parts:

1. Hardware

2. Software

• Operating system software

• DBMS software

• Application programs and utility software

3. People

4. Procedures

5. Data

Data Model and Conceptual

Modeling


• Designers, programmers, and end users

see data in different ways• Different views of same data lead to design

that do not reflect organization’s operation• Data modeling reduces complexities of

database design

• a simple representations of complex real-world data structures (Often graphical)

• a model: an abstraction of a real-world object or event

• Useful in understanding complexities of the real-world environment

• is iterative and progressive


Modeling


Data Modelling is :Important in order to /

because:

• Facilitate interaction

among the designer,

applications programmer,

and end user• End users have different

views and needs for data• Data model organizes data

for various users

Model Building

Blocks


Modeling


ATTRIBUTE

ENTITY

RELATIONSHIP

CONSTRAINT

Business Rules

•Descriptions of policies, procedures•Apply to any organization •Description of operations to create/enforce

actions •Must be in writing and up to date• Must be easy to understand


Modeling


Translate Bussiness Rules => Data Model

• nouns translate into entities

• Verbs translate into relationships

• Relationships are bidirectional


Modeling



Modeling


Conceptual Modelling• Represents global view of the entire database• All external views integrated into single global view: conceptual

schema• ER model most widely used• ERD graphically represents the conceptual schema• Provides a relatively easily understood macro level view of data

environment• Independent of both software and hardware • Does not depend on the DBMS software used to implement the

model • Does not depend on the hardware used in the implementation of

the model• Changes in hardware or software do not affect database design

at the conceptual level


Modeling


Conceptual Modelling

• A student can enroll at least

one or more subjects and a subjects

can be enrolled with more than one

students.

• It is an optional for a lecturer

to teach and a lecturer also can

teach more than one subjects.

• Enrollment must have one

subjects and subject can be offered

more than one as it is also optional

for a subject to be offered in any

semester.

Business Rules

1

44

DBMS Functions


• Performs functions that guarantee integrity and consistency of data.

• Data transformation and presentation• Security management• Multiuser access control• Backup and recovery management• Data integrity management• Database access languages and application programming

interfaces• Database communication interfaces

1

50

• Data are raw facts. Information is the result of processing data to reveal its meaning.

• To implement and manage a database, use a DBMS.• Database design defines the database structure.• A well-designed database facilitates data management

and generates accurate and valuable information.• A poorly designed database can lead to bad decision

making, and bad decision making can lead to the failure of an organization.

SUMMARY

1

51

• Databases were preceded by file systems.

• Limitations of file system data management: – requires extensive programming– system administration complex and difficult– making changes to existing structures is difficult– security features are likely to be inadequate– independent files tend to contain redundant data

• DBMS’s were developed to address file systems’ inherent weaknesses

SUMMARY

Introduction To Database System

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