03-er-diagrams(2) - copy

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Database Design


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Phases of Database Design

Conceptual designbegins with the

collection of requirements and results

needed from the database (ER Diag.)

Logical schema is a description of the

structure of the database (Relational,

Network, etc.)

Physical schema is a description ofthe implementation (programs, tables,

dictionaries, catalogs

Data

Requirements

Conceptual

Design

Logical

Design

Physical

Design

Conceptual Schema

Specification of requirements

and results

Logical Schema

Physical Schema


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Models

A data modelis a collection of objects that

can be used to represent a set ofdata and

operations to manipulate the dataConceptual models are tools for representing

reality at a veryhigh-level of abstraction

Logical models are data descriptions that canbe processed by computers


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Conceptual model:

Entity-Relationship Diagrams

Entities represent classes ofreal-world

objects. Person, Students, Projects, Courses

are entities of a University databaseRelationships represent interactions

between two or more entities

Pers

Is_B r _I

it

ives_I

N1

N 1


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Example:

Every employee works in at least one

project

Every project has employees working on it.

EMPLOYEE

SSNName

Salary

PROJECT

Name

Code

WORKS ONN

N


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Higher-Order Relationships

A relationship may involve more than two

entities

Course Meets Cl ssr oom

Day


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Recursive relationships

Relationships could be mapped from one

entity to itself

Manager_Of

Employee Manages

Subordinate_To

1

N


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Attributes

Attributes represent elementary properties of the

entities or relationships. The stored data will be

kept as values of the attributes

PERSON

Ssn

Name

Profession

Is orn In

CITY

NameCountry

Ele ation

Population

Li es InN 1

N 1

irth Date

Mo ing Date


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Generalizations

MAN

Draft Status

FEMALE

Maiden Name

PERSON

Ssn

Name

Address

An entity could beseen from many different viewpoints

Each viewpoint defines a set ofroles in a generalization

Example below uses SEXto classify the object Person


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Generalizations

A classification could be disjointor

overlapping

An entity could have more than oneclassification

MAN

Draft_ tatus

FEMALE

Mai en_ ame

PERSON

Ssn

Name

Address

SEX

Full_Tim

Annual_Salary

Department

Part_Tim

Hour_ ate

Weekly_Hours

OB


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Example: Department Store 1/2

A department store operates in several

cities

In a city there is one headquartercoordinating the local operations

A city mayhave several stores

Stores hold any amount of itemsCustomers place their orders for any

number of items to a given store

GOAL: Optimize shopping in each city


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Example: Department Store 2/2

CITIES

City Na e

State

HeadQtrAddress

STORES

Store ID

Address

Manager ID

LOCATED

IN

ITEMS

Item ID

Description

Size

Color

ORDERS

OrderNumber

OrderDate

ITEMSORDERED

Qty Ordered

HOLD

Qty Held

IN-CITIES

Qty_in_cities

CUSTOMER

CustomerName

Address

PhoneNumber

PLACE

N

N

1

N

N N

N N N

1


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Example: University Database

Professors work for only one department

Departments have many professors

Each course is taught by only one professor

Students make aplan orprogram of study

A course could meet in several rooms/times

Graduate students must have an advisor

Cities are categorized as resident/BirthPlace

Visiting prof. need an End/Start date


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University Database

University database

BIRT PLACE

CITY

NameState

PERSON

LastNameAge

PROFESSOR

TenureStatus

Title

STUDENT

DEPARTMENT

NamePhone Belongs To

ENROLLED

Semester

Grade

PLANNED

SemesterGRADUATE_STUDENT ADVISED BY

VISITING_

PROFESSOR

Start Appointment

End Appointment

COURSE

Title

Description

Credits

TAUG T BY

Semester

MEETS

ROOM

RoomNumber

Building

TIME

Day

our

RESIDENT

1 N

N

N

N

N

N

N

1

N N

N 1

1

N

N

1


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Soccer Database

A team has players, one coach, fans

Teams play according to a schedule

Teams need to practice in a Stadium

Attendance and scores must be recorded


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Soccer Database

FAN

Name

Address

Favori

e

ar

PLAYERUni

orm_Si e

Shoe_Sie

PERSON

Ssn

Name

Address

COACHPersonal Record

Years

xperience

SUPPORTSPLAYS

_FORMANAG

S

TEAM

Name

Location

Phone

PLAY_

AGAINST

GAME

Number

Attendance

Final ScoreDate

TAK

S

PLAC

AT

PRACTIC

S

STADIUM

Name

Address

Capacity

ATT NDS

N

N1

N 1

1

N N N 1

N

N

N N


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ResearchProject Database

Some employees are researchers

Every project has a leader investigator

Every project must be funded by an agency

A project may include several topics

A topic could appear in several projects

Researchers must produce report(s)

Each employee must have a supervisor


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ResearchProjects Database

RESEARCH TOPIC

Code

Name

RESEARCH REPORT

Number

Title

EMPLOYEE

SSN

Name

Title

ADDRESSES PRODUCES

PRINCIPAL

INVESTIGATORRESEARCH

PROJECT

NameCode

FUNDED

BY

Amount

Date

Grant#

AGENCY

Name

Address

Contact Person

WORKS

ON

N

N

N

N

N

N

SUPERVISE

S

N 11

1 N

N

ON

N

NN


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Contract-Supplies System 1/3

A company negotiates contracts with

suppliers to provide certain amount of items

at a fixed priceOrders are placed against any of the already

negotiated contracts

A contract could provide items to anynumber of orders


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An order may include any number of items

negotiated in the contract

Orders should not exceed the maximumamount of items quoted in the contract

All items in an order must be provided as

part of a single contract and a single project


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SUPP IERS

Supplier Nu ber

Na

e

Address

N

IA

Date of Contract

C

N

RAC

S

Contract Nu

ber

ext

I

ES

Ite

Nu

ber

Description

SUPPLY

Contract Price

Contract A

ount

AD

rder Q

Y

RDERS

rder Nu ber

Date Required

Date Co pleted

SUPPLI

D AS

N

D

D

Y

PR

JEC

S

Project Nu

ber

Project Data

1

N

1 N

N

N

N N

1

N


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Manufacturing: Requisitions 1/3

Projects are broken into tasks

Tasks are assigned to departments

A task is created for one project andassigned to one department

Requisitions are made for projects

Each requisition could ask for any numberof items


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Each requisition is for one project and is

made to one supplier

Items could be: equipmentormaterials andare coded in a similar way

Suppliers send periodic price notices to

advise the company of any changes in theirprices


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SUPPLIERS

Supplier

Number

SupplierData

PROJECTS

Project Number

Project Data

MADE OFTASKS

TaskNumber

TaskData

REQUESTS

REQUISITION

ItemNumber

QtyRequested

CONTAINS

ITEMS

ItemNumber

ItemData

EQUIPMENTITEM

Code

Description

MATERIALITEM

Code

Description

WeightContainer

CHANGESPRICEADVICE

Price

EffectiveDate

SENDS

FROM

FOR

REQUISITION

ItemNumber

QtyRequested

1 N

N

1

N

1

N 1

N

N

1 N

N

1


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Job-Shop Accounting System 1/4

The system is used by a company that

manufactures special-purpose assemblies

for customersTo manufacture assemblies the company

creates a sequence of processes (steps)

Each process is supervised by a departmentAssume there are three type of processes:

PAINT, FIT,CUT


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During manufacturing an assembly could

pass through any sequence of processes, in

any order; it may pass through the sameprocess more than once

A unique Job# is given to any new

assembly.

Costs and started-terminated dates must be

recorded


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An accounting system is used to keep track

expenditure for each: DEPT,

PROCESS,

ASSEMBLY

As a job proceeds, cost transactions can be

recorded against it.


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Job-Shop Accounting System 4/4CUSTOMER

S

Customer ID

Address

ORDERS

ASSEMBLIE

S

Assembly ID

Date Ordered

Details

CUT JOBS

Cut Job ID

Machine type

used

Material used

Laor time

JOBS

Job Number

Starting Date

Ending Date

Total Cost

FIT JOBS

Fit Job ID

Labor time

PAINT JOBS

Paint Job ID

Color

Volume

Labor time

A1

ACTIVITY

USES

MADE AS

TRANSACTIONS

PROCESS

ACCOUNTS

Account 3

Details

DEPT

ACCOUNTS

Account 2

Details

ASSEMBLY

ACCOUNTS

Account 1

Details

ACCOUNTS

Account ID

Date

Established

PROCESSES

Process ID

Process Data

DEPARTMENT

S

Dept Number

Dept Data

A2

T1

T3

T2

USED IN A3

CUT PROC

Cut Proc ID

Cuttong TypeMachine Type

FIT PROC

Fit Proc IDFit Type

PAINT PROC

Paint Proc IDPaint Method

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