lesson 2 database

7/31/2019 Lesson 2 Database

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MBADavid Asirvatham


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msuUniversity of ChoiceDavid Asirvatham

Database Systems

Database Model

There four database models: Relational Database Model

Object-Oriented Database Model

Hierarchical Database Model

Network Database Model

the Hierarchical and Network database models arethe oldest and least used


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Database Systems

Relational Database

Most widely used database

it uses a series of two dimensional tables or files

e.g. Partsfile &Customerfile (in earlier example)

each table stores data pertaining to a particular

entity class

An entity class is a concept of things (or people orplaces) that are stored in the database

example of entity class are parts, customers orstudents

an instance (record) is an occurrence of an entityclass


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Database Systems

Relational Database

It is built on a simple concept of representing datain a two-dimensional tables

easy to identify the entity class


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Database Systems

Object-oriented Database

might be tomorrows database (future)

it is based on objects

an entity class in object-oriented database is similar

to the entity class in a relational database

in object-oriented, the object includes orencapsulates both information about a specificentity class and the software instruction

(procedures) to work on the information.


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Database Systems

Object-oriented database

CustomerInformation:

Customer ID

Name

Phone

Address

Procedures:

Add new customer

Get Customer Information

Change Address

Save Customer information

PartsInformation:

Part #

Description

Quantity

Price

Procedures:

Add new part

Get part Information

Update quantity

Save Part information

Object representation


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Database Systems

OODB

OODB allows you to work with bothdata/information and procedures

object-oriented database management (OOBDMS) isa DBMS software that allows you to develop and

work with OODB

advantages of OODB combines data and procedures thus closer to the way organisations work

reusable (e.g. a Video Rental object may contain Customer object)


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Database Systems

OODB

CustomerInformation:

Customer ID

Name

Phone

Address

Procedures:

Add new customer

Get Customer Information

Change Address

Save Customer information

Video RentalInformation:

CUSTOMER

VIDEO

Date Rented

Date Returned

Procedures:

Create new Video Rental

Calculate total Price

Get Video Rental Info

Save Video Rental

Related

Objects


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Database Systems

Step 1: Defining Entity Classes

Identity the entity classes e.g. Employee, Department and Job

Identity the primary key e.g. for Employee it is Emp ID

for Department it could be Dept. Code


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Database Systems

Step 2: Defining Relationships

Entity-Relationship (ER) diagram may be used

There are 7 symbols used in ER: a rectangle to denote an entity class

a diamond to denote a relationship between two entity classes

a line to connect symbols

a 1 to denote a single occurrence

a M to denote multiple occurrence

An o to denote an optional relationship


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Database Systems

Step 2: Defining Relationship

How to read?

Follow arrow A and B

A :An Employee is assigned to one and must be assigned to one department.

B:A Department may have many employees assigned or may not have

any employee assigned to it.

EMPLOYEE DEPARTMENTM:1

A

B


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Database Systems

Step 2: Defining Relationship

EMPLOYEE DEPARTMENTM:1

JOBM:M


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Database Systems

Step 2: Defining Relationship(Normalisation)

After drawing the ER diagram, you will need tonormalise it

Normalisation is a process of assuring that arelational database structure can be implemented as

a series of tables

There are 3 basic rules for normalisation eliminate repeating groups (i.e. M:M relationships)

assure that each field in a relation depends only on the primary key of

that relation

remove all derived fields from the relations


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Database Systems

Step 2: (Normalisation)

JOBM:MEMPLOYEE

JOBM:1EMPLOYEE-JOBEMPLOYEE 1:M

Primary Key

Emp ID

1345

3758

3899

4571

Primary Key

Emp ID

13453758

3899

4571

Primary Key

Job Code

17

22

2532

Primary Key

Job Code

1722

25

32

Primary Key

Emp ID + Job Code

1345 + 171345 + 25

3758 + 17

3899 + 25

3899 + 32

4571 + 22

4571 + 25


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Database Systems

Step 3: Defining fields for each Relation

To determine the data that will be in a relation, wemust ask Does this data depend only on theprimary key for this relation?

If yes, then it is in the right relation

Example: Employee (Emp ID, Name, Dept., Dept. Location)

Job (Job Code, Job Name)

Department (Dept., Dept. Location, Number of Employees)

Employee-Job (Emp ID, Job Code, Hours)


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Database Systems

Step 4: Use DDL to create the database

Use the DDL to create the relations

define the data dictionary

set the primary key and properties of each field


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Database Systems

Data Warehouse

A data warehouse is a logical collection ofinformation- gathered from many differentoperational databases - that supports businessanalysis activities and decision-making tasks

it combines information from different databases

gather only the required information for decision-making

require information is defined by the user


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Database Systems

Data Warehouse

most data warehouses are multidimensionaldatabases - they contain layers of columns and rows(this is called hybercube)

Product

3

Penang

Ipoh

KL

Melaka

JB

Product

1

Product

2

Product

4

Product

5

Year

Credit

What percentage of the total sales for

product 3 in Ipoh were credit sales?


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Database Systems

Data warehouse

Data warehouse also has a data dictionary

the data dictionary maintains: logical structure of the information

origin (source database)

methods (e.g. total, count, average, std deviation, etc)

Data warehouse supports online analyticalprocessing most database support online transaction processing


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Database Systems

Data Mining Tools

Data mining tools are software tools used to query

information in a data warehouse

it supports online analytical processing

Data mining includes:

Query-and-Reporting Tools

Intelligent Agents

Multidimensional Analysis Tools

DATA

WAREHOUSE

DATA

WAREHOUSE

ENGINE

Query-and-Reporting Tools

Intelligent Agents



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msuU f hDavid Asirvatham

Database Systems

Data Mining Tools

Query-and-Reporting Tools use similar tools as QBE, SQL and report generation tools

Intelligent Agents uses artificial intelligence tools such as neural networks and fuzzy logic to

form the basis of information discovery e.g. Data/Logic is used by some Wall Street analyst

e.g. Data Engine


is a slice-and-dice technique allows a user to view multidimensional information

e.g. Forest & Trees (North Memorial Medical Centre which has 10,000daily patient records)

lesson 2 database

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