Chapter 1-Introduction to Database System

Database System EC601

MRS. ISMA SHAMSURIA BINTI ISMAIL

Department of Electrical Engineering (LEVEL 1)The Polytechnic of Merlimau, Melaka

019-4211728 ext:1163

DATABASE SYSTEM course offers a comprehensive

coverage of basic concept and application of data

manipulation. Student will learn the fundamental

concepts and techniques for designing and developing

database and manipulating data using Structured Query

Language (SQL).

Course Outline

NOCOURSE LEARNING OUTCOMES

(CLO)PLO

LEARNING

DOMAINS

1 Explain the basic concepts of database model using entity-relationship diagram and translating completed data models by applying normalization technique in logical database designs.

PLO 1

PLO 2

PLO 9

C4

2

Apply Structured Query Language (SQL) for database manipulation using a database management system in practical works inclusive of a report within stipulated time frame.

P4

3

Demonstrate problem solving skill in developing new database applications based on an assigned problem.

A3

CLO Types Of Assessment

Percentage

(%)

1. CONTINUOUS

ASSESSMENT (CA) 50

CLO1 i. Quiz (minimum 4) 20 CLO1 i. Theory Test (minimum 1) 20 CLO1, CLO2, CLO3

i. Practical Work (minimum 6)

50

CLO3i. Presentation (minimum

1)10

1. FINAL EXAMINATION (FE) 50Total 100

Introduction ToDatabase System

CHAPTER ONE

CLO 1 : Explain the basic concepts of database

model using entity-relationship diagram and

translating completed data models by applying

normalization technique in logical database

designs.

DATA are raw facts used to indicate that the facts have not yet been

processes.

- Data can be recorded and that have implicit meaning. For

example, consider the names, telephone numbers, and

addresses of the students.

INFORMATION is produced by processing data used to reveal the

meaning of data.

- For example, student information record including the names, telephone

numbers, and addresses of the students.

DATABASE

– A collection of data stored in a standardized format,

designed to be shared by multiple users.

DATABASE MANAGEMENT SYSTEM (DBMS)

– Software that defines a database, stores the data,

supports a query language, produces reports, and

creates data entry screens.

A DATABASE has some source from which data is derived,

some degree of interaction with events in the real world, and

an audience that is actively interested in its contents.

The end users of a database may perform business

transactions (for example, a students pays a fee) or events

may happen (for example, a polytechnic has a student) that

cause the information in the database to change.

No Level Description

1. Character basic logical data element. It consists of a single alphabetic, numeric, or other symbol.

2. Field It consists of a grouping of characters. A data field represents an attribute (a characteristic or quality) of some entity (object, person, place, or event).

3. Record A group of the related fields of data Represents a collection of attributes that describe an entity.

4. File A group of related records Frequently classified by the application for which they are primarily used Also classified by their permanence, for example, a master file versus a transaction file.

5. Database An integrated collection of logically related records or objects. A database consolidates records previously stored in separate f files into a common pool of data records that provides data for many applications.

Uncontrolled Duplication Wastes space Hard to update all files

Inconsistent data Inflexibility

Hard to change data Hard to change programs

Limited data sharingPoor enforcement of standardsPoor programmer productivityExcessive program maintenance

Database Management System (DBMS)

File-based System

Database System

1. DBMS - a computer software program that enables users to

access, create and maintain a database.

2. DBMS is also the combination of data, hardware, software

and users to help an enterprise manage its operational data.

3. The main function of a DBMS - to provide efficient and

reliable methods of data retrieval to many users.

4. The general-purpose of DBMS - facilitates the processes of

defining, constructing, manipulating, and sharing databases

among various users and applications.

No Process Description

1. Defining specifying the data types, structures, and constraints of the

data to be stored in the database.

Data files - files that store the database information

Meta-data - such as index files and data dictionaries, store

administrative information.

2. Constructingprocess of storing the data on some storage medium that is

controlled by the DBMS.

3. Manipulating functions such as querying the database to retrieve specific

data, updating the database to reflect changes in the

miniworld, and generating reports from the data.

4. Sharingallows multiple users and programs to access the database

simultaneously.

Advantages of Database Approach

Minimal data redundancy.

Data consistency.

Integration of data.

Sharing of data.

Enforcement of standards.

Ease of application development.

Uniform security, privacy and integrity.

Data independence.

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Data is most important Data defined first Standard format

Access through DBMS Queries, Reports, Forms Application Programs 3GL Interface

Data independence Change data definition without

changing code Alter code without changing data Move/split data without changing

code16

All Data

DBMS

Program1 Program2QueriesReports

Oracle

Ingres

Informix (Unix)

DB2, SQL/DS (IBM)

Access (Microsoft)

SQL Server (Microsoft +)

Many older (Focus, IMS, ...)

Many limited PC (dBASE, Paradox, …)

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A file based system - a collection of application

programs that perform services for the end-users, usually

the production of reports.

Each program within a file based system defines and

manages its own data - there are limits as to how that

data can be used or transported.

Were developed as better alternatives to paper based

filing systems.

Files stored on computers - the data could be accessed

more efficiently.

Common practice for larger companies - each of its

departments looking after its own data.

The PROBLEMS of file based system are:

Data separation and isolation

Data dependence

Data duplication

Incompatible data (different file formats)

Lack of flexibility in organizing and querying the data

Increased number of different application programs

Database system is a system to achieve an organized,

store a large number of dynamical associated data, facilitate

for multi-user accessing to computer hardware, software

and data, that it is a computer system with database

technology.

The database approach emerged to resolve the problems

with the file-based approach.

Sharing of data

Consistency of data

Integrity of data

Security of data

Data independence

Allows for more analysis of

the same amount of data

Advantages of database systems are:

Improved data access and

system performance

Potentially increased

productivity

Increased concurrency

Improved data backups and

recovery

The main characteristics of the database approach versus the file processing approach are the following:

1. Self-describing nature of a database system

2. Insulation between programs and data, and data

abstraction

3. Support of multiple views of the data

4. Sharing of data and multiuser transaction processing

Database System contains not only the database itself

but also the descriptions of data structure and

constraints (meta-data) - used by the DBMS software or

database users if needed.

This separation makes database system totally different

from traditional file-based system in which data

definition is a part of application programs.

2. Insulation between Program and Data

In the filed base system, the structure of the data files is

defined in the application programs so if user want to

change the structure of a file, all the programs access to

that files might need to be changed.

In database approach, data structure is stored in the

system catalog not in the programs so such changes

might not occurs.

3. Support multiple views of data

A view is a subset of the database which is defined

and dedicated for particular users of the system.

Multiple users in the system might have different views

of the system.

Each view might contains only the interested data of

an user or a group of user.

4. Sharing of data and Multiuser system

A multiuser database system must allow multiple

users access the database at the same time.

As the result, the multiuser DBMS must have

concurrency control strategies to ensure that several

user try to access the same data item at a time do

so in the manner so that the data always be correct.

Airlines and railwaysBankingTelecommunicationsEducation

Credit card transactionsE-commerceHealth care information

systems and electronic patient record

Digital libraries and digital publishing

FinanceSalesHuman resources

1. PERSONAL DATABASE

Also known as a SINGLE USER Database / a

DESKTOP Database

Supports only one user at a time

User B or C must wait until user A has completed his

database work.

2. WORKGROUP DATABASE

Also known as a MULTIUSER Database

Supports a relatively small number of users (<50)

A specific department within an organization using the

same database – DEPARTMENT DATABASE

3. ENTERPRISE DATABASE

The database used by the entire organization

Supports MANY users (>50) across many departments

The DBMS acts as an interface between what two

components of an enterprise-class database

system?

A. Database application and the database

B. Data and the database

C. The user and the database application

D. Database application and SQL

A

The following are components of a database

except ________ .

A. user data

B. metadata

C. reports

D. indexes

C

An application where only one user accesses the

database at a given time is an example of a

________ .

A. single-user database application

B. multiuser database application

C. e-commerce database application

D. data mining database application

A

An on-line commercial site such as Amazon.com is

an example of a ________ .





C

Metadata enables database designers and users to

do all of the following except:

A. sample data.

B. understand what data exist.

C. what the fine distinctions are between similar data

items.

D. what the data mean.

A

A database management system (DBMS) is a:

A. hardware system used to create, maintain, and provide controlled

access to a database.

B. hardware system used to create, maintain, and provide uncontrolled


C. software system used to create, maintain, and provide controlled


D. software system used to create, maintain, and provide uncontrolled


C

Because it contains a description of its own structure, a

database is considered to be ________ .

A. described

B. metadata compatible

C. self-describing

D. an application program

C

The following are functions of a DBMS except

________ .

A. creating and processing forms

B. creating databases

C. processing data

D. administrating databases

A

Structured data may include which of the following?

A. Photo image

B. Video clip

C. Dates

D. None of the above.

C

Helping people keep track of things is the purpose of a(n)

________ .

A. database

B. table

C. instance

D. relationship

A

Some advantages of the database approach include all, but:

A. minimal data redundancy.

B. improved data consistency.

C. improved data sharing.

D. program-data dependency.

D

An Enterprise Resource Planning application is an example of

A ________ .





B

1. In a database, data is stored in spreadsheets which have rows and columns.

2. A database has data and relationships.

3. In an enterprise-class database system, business users interact directly with database applications, which directly access the database data.

4. Applications are programs that interact directly with the database.

5. A database has a built-in capability to create, process and administer itself.

6. A database design may be based on existing data.

7. A workgroup typically comprises between 25 and 100 persons.

MODEL

A Model is representation of reality, ’real world’ objects and

events and their associations.

A database model is an organizing principle that specifies

particular mechanism of data storage and retrieval.

The model explains, in terms of services available to an

interfacing application, how to access a data element when

other related elements are known.

Data Model is a collection of concepts that can be used to describe the structure of database.

Structure of database means data types, relationships and constraints.

In addition, most data model include a set of basic operations for specifying retrievals and modifications on the database.

Data Model provides a means to achieve Data Abstraction. Data Abstraction is refers to the hiding of certain details of

how the data are stored and maintained. With several levels of abstraction, the user’s view of the database is simplified and this leads to the improved understanding of data.

The major purpose of a database system is to provide users with an abstract view of the system.

Complexity should be hidden from database users. There are 3 levels of abstraction:

Levels of Abstraction

Description

Physical level how the data is stored physically and where it is stored in database.

Logical level what information or data is stored in the database (like what is the data type or what is format of data)

View level end users work on view level. if any amendment is made it can be saved by other name.

• Views describe how users see the data.

• Conceptual schema defines logical structure

• Physical schema describes the files and indexes used.

Physical Schema

Conceptual Schema

View 1 View 2 View 3

DB

Users

Purpose of Data Model

To represent data.

To make the data understandable.

Types of Data Models

1. Object Based Data Models

2. Physical Data Models

3. Record Based Logical Data Models

1. Object Based Data Models

It use concepts such as entities, attributes and

relationships.

Types of Object Based Data Models:

Entity Relationship (ER)

Object Oriented

Semantic

Functional

a. The Entity Relationship (ER) Model

Based on a perception of the world as consisting of a collection of basic objects (entities) and relationships among these objects. An entity is a distinguishable object that exists. Each entity has associated with it a set of attributes

describing it. A relationship is an association among several entities. The set of all entities or relationships of the same type is

called the entity set or relationship set. Another essential element of the E-R diagram is the mapping

cardinalities, which express the number of entities to which another entity can be associated via a relationship set.

Database System Design

User viewsof data.

Conceptualdata model.

Customer(CustomerID, Name, Address, …)

SalesPerson(EmployeeID, Name, Commission, … )

Order(OrderID, OrderDate, CustomerID, EmployeeID, … )

OrderItem(OrderID, ItemID, Quantity, Price, … )

Item(ItemID, Description, ListPrice, …)

Implementation(relational)data model.

Physicaldatastorage.

Class diagram that shows business entities, relationships, and rules.

List of nicely-behaved tables. Use data normalization to derive the list.

Indexes and storage methods to improve performance.

The Entity Relationship (ER) Model sample diagram

b. The Object-Oriented Model

Based on a collection of objects - class, like the E-R model. An object contains values stored in instance variables

within the object. Unlike the record-oriented models, these values are

themselves objects. Thus objects contain objects to an arbitrarily deep level of

nesting. An object also contains bodies of code that operate on

the object. These bodies of code are called methods.

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CustomerCustomerIDName… Add CustomerDrop CustomerChange Address

OrderOrderIDCustomerID… NewOrderDeleteOrder…

OrderItemOrderIDItemID… OrderItemDropOrderItem…

ItemItemIDDescription… New ItemSell ItemBuy Item …

GovernmentCustomer

ContactNameContactPhoneDiscount, …

NewContact

CommercialCustomer

ContactNameContactPhone…

NewContact

c. Semantic

ABSTRACTIONS:

• CLASSIFICATION

• AGGREGATION

• GENERALIZATION

d. FunctionalProvides an unified approach to manipulation both data and procedures. Main idea - is a definition of all components of an information system in the form of functions. Example: defines data objects, attributes and relationships as so-called database functions. A Functional Data Manipulation Language is a number of data manipulation functions which can be applied to database functions. Users are provided with a special mechanism which is called Lambda Calculus to define their own functions which can be seamlessly combined with database and data manipulation functions mentioned above.

Functional Data model Diagram

2. Physical Data Models

It describe how data is stored in the computer, representing

information such as record structures, record ordering and access

paths.

Less no. of models are there.

Are used to describe data at the lowest level.

Very few models, e.g.

Unifying model.

Frame memory.

3. Record Based Logical Data Models

Used to specify the overall logical structure of the database. The database consists of a no. of fixed formats of different types. Each record type defines a fixed no. of fields having a fixed length.

3 types of record based data model:

a. Hierarchical data model.

b. Network data model.

c. Relational data model.

a. The Hierarchical Model

Similar to the network model.

Organization of the records is as a collection of trees,

rather than arbitrary graphs.

The relational model does not use pointers or links, but

relates records by the values they contain. This allows a

formal mathematical foundation to be defined.

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Customers

Orders

Item Description Quantity998 Dog Food 12764 Cat Food 11

Items

Customer

Order

Items Ordered

To retrieve data, you must start at the top (customer). When you retrieve a customer, you retrieve all nested data.

b. The Network Model

Data are represented by collections of records.

Relationships among data are represented by links.

Organization is that of an arbitrary graph.

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Customer

OrderItems

Ordered

Items

Entry point

Entry point

c. The Relational Model

Data and relationships are represented by a collection of

tables.

Each table has a number of columns with unique names,

e.g. customer, account.

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Customer(CustomerID, Name, …

Order(OrderID, CustomerID, OrderDate, …

ItemsOrdered(OrderID, ItemID, Quantity, …

Items(ItemID, Description, Price, …

Schema

Logical structure of database.

The description of the database which is designed in the

early stage and is not expected to change frequently.

Database system have several schemas.

Example:

Book (Bid: char(2), Title: char(50), Author:char(20),

Price: decimal(5,2))

Instance

Actual content of database at particular moment.

Since information can be inserted to or deleted from

database at anytime, database changes over time.

Example:Bid Title Author Price

11 Franklin forgets Bourgeois 7.00

22 Arthur and the Seventh-Inning Stretcher Krensky 14.00

33 Midnight Wrestlers Morgan 11.00

44 Midnight Pilot Morgan 9.00

55 Book of Science Activities 18.00

DATA DEFINITION LANGUAGE (DDL)

Specification notation for defining the database schema

DDL compiler generates a set of tables stored in a data

dictionary – meta data (data about data)

Data storage and definition language – special type of

DDL in which the storage structure and access method

used by the database system are specified

CREATE DATABASE - Creates a new database

ALTER DATABASE - Modifies the database

DROP DATABASE - Drops (deletes) a database

CREATE TABLE - Creates a new table

ALTER TABLE - Modifies the table

DROP TABLE - Drops (deletes) a table

DATA MANIPULATION LANGUAGE (DML)

Language for accessing and manipulating the data organized

by appropriate data model

2 classes of language :

Procedural – user specifies what data required and how to get

those data

Nonprocedural – user specifies what data required without

specifying how to get those data

SELECT - Retrieves data from the database

INSERT - Inserts new data into the database

UPDATE - Updates existing data in the database

DELETE - Deletes existing data from the database

4G LANGUAGE (4GL)

Fourth-generation programming language (1970s-1990)

A very high level programming language and a development

environment or 'Analyst Workbench' designed with a central

data dictionary system, a library of loosely coupled design

patterns, a CRUD generator, report generator, end-user query

language, DBMS, visual design tool and integration API.

4G LANGUAGE (4GL)

4GL is more oriented toward problem solving and systems

engineering.

Not always successful in this task, sometimes resulting in

inelegant and unmaintainable code. However, given the right

problem, the use of an appropriate 4GL can be spectacularly

successful.

Are designed to reduce programming effort, the time it takes

to develop software, and the cost of software development

1. HARDWARE

All system’s physical devices

Main component – computer and computer peripherals

Networks

DBMS COMPONENT MODULES

2. SOFTWARE

OS software - Manages all hardware components

DBMS software – Manages the database within the

database system

Application programs and utility software – access and

manipulate data in DBMS


3. USERS/PEOPLEapplication programmers, non-computer science expert and

experienced user, database designers, system administrators

4. PROCEDURES Instructions and rules that govern the design and use of

database systemUsed to ensure that there is an organized way to monitor and

audit both data enter and information that is generated

5. DATACollection of facts stored in database


Which of the following database activities determines the

entities, attributes, and relationships of data?

A. Conceptual data modeling

B. Logical database design

C. Physical database design and definition

D. Database implementation

A

An entity type is which of the following?

A. A major category of data about people, place, and things

B. The various departments of an organization

C. The application software

D. The business processes the support the mission of an

organization

A

Which of the following database activities require a specific

knowledge of a DBMS?

A. Enterprise modeling

B. Conceptual data modeling

C. Logical database design

D. Physical database design and definition

D

User views are included as part of which schema?

A. Internal

B. Conceptual

C. External

D. None of the above.

C

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Chapter 1-Introduction to Database System