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Database Design

Victor Matos

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Phases of Database Design

Conceptual design begins 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 of

the 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 model is a collection of objects that

can be used to represent a set of data and

operations to manipulate the data

Conceptual models are tools for representing

reality at a very high-level of abstraction

Logical models are data descriptions that can

be processed by computers

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Conceptual model:

Entity-Relationship Diagrams

Entities represent classes of real-world

objects. Person, Students, Projects, Courses

are entities of a University database

Relationships represent interactions

between two or more entities

Person

Is_Born_In

City

Lives_In

N 1

N 1

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Example:

Every employee works in at least one

project

Every project has employees working on it.

EMPLOYEE

SSN

Name

Salary

PROJECT

Name

Code

WORKS_ONNN

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Higher-Order Relationships

A relationship may involve more than two

entities

Course Meets Classroom

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_Born_In

CITY

Name

Country

Elevation

Population

Lives_InN 1

N 1

Birth_Date

Moving_Date

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Generalizations

MAN

Draft_Status

FEMALE

Maiden_Name

PERSON

Ssn

Name

Address

• An entity could be seen from many different viewpoints

• Each viewpoint defines a set of roles in a generalization

• Example below uses SEX to classify the object “Person”

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Generalizations

A classification could be disjoint or

overlapping

An entity could have more than one

classification

MAN

Draft_Status

FEMALE

Maiden_Name

PERSON

Ssn

Name

Address

SEX

Full_Time

Annual_Salary

Department

Part_Time

Hour_Rate

Weekly_Hours

JOB

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Example: Department Store 1/2

A department store operates in several

cities

In a city there is one headquarter

coordinating the local operations

A city may have several stores

Stores hold any amount of items

Customers 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 Name

State

HeadQtr Address

STORES

Store ID

Address

Manager ID

LOCATED

IN

ITEMS

Item ID

Description

Size

Color

ORDERS

Order Number

Order Date

ITEMS ORDERED

Qty Ordered

HOLD

Qty Held

IN-CITIES

Qty_in_cities

CUSTOMER

Customer Name

Address

Phone Number

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 a plan or program 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

BIRTH_PLACE

CITY

Name

State

PERSON

LastName

Age

PROFESSOR

TenureStatus

Title

STUDENT

DEPARTMENT

Name

Phone

Belongs_To

ENROLLED

Semester

Grade

PLANNED

SemesterGRADUATE_STUDENT ADVISED_BY

VISITING_

PROFESSOR

Start_Appointment

End_Appointment

COURSE

Title

Description

Credits

TAUGHT_BY

Semester

MEETS

ROOM

RoomNumber

Building

TIME

Day

Hour

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

Favorite Bar

PLAYER

Uniform_Size

Shoe_Size

PERSON

Ssn

Name

Address

COACH

Personal Record

Years Experience

SUPPORTSPLAYS

_FORMANAGES

TEAM

Name

Location

Phone

PLAY_

AGAINST

GAME

Number

Attendance

Final Score

Date

TAKES

PLACE

AT

PRACTICES

STADIUM

Name

Address

Capacity

ATTENDS

N

N1

N 1

1

N N N 1

N

N

N N

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Research Project 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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Research Projects Database

RESEARCH TOPIC

Code

Name

RESEARCH REPORT

Number

Title

EMPLOYEE

SSN

Name

Title

ADDRESSES PRODUCES

PRINCIPAL

INVESTIGATORRESEARCH

PROJECT

Name

Code

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 price

Orders are placed against any of the already

negotiated contracts

A contract could provide items to any

number of orders

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Contract-Supplies System 2/3

An order may include any number of items

negotiated in the contract

Orders should not exceed the maximum

amount 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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Contract-Supplies System 3/3

SUPPLIERS

Supplier Number

Name

Address

NEGOTIATE

Date of Contract

CONTRACTS

Contract Number

Text

ITEMS

Item Number

Description

TO SUPPLY

Contract Price

Contract Amount

MADE OF

Order QTY

ORDERS

Order Number

Date Required

Date Completed

SUPPLIED AS

NEEDED BY

PROJECTS

Project Number

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 and

assigned to one department

Requisitions are made for projects

Each requisition could ask for any number

of items

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Manufacturing: Requisitions 2/3

Each requisition is for one project and is

made to one supplier

Items could be: equipment or materials and

are coded in a similar way

Suppliers send periodic price notices to

advise the company of any changes in their

prices

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Manufacturing: Requisitions 3/3

SUPPLIERS

Supplier

Number

Supplier Data

PROJECTS

Project Number

Project Data

MADE OF

TASKS

Task Number

Task Data

REQUESTS

REQUISITION

Item Number

Qty Requested

CONTAINS

ITEMS

Item Number

Item Data

EQUIPMENT ITEM

Code

Description

MATERIAL ITEM

Code

Description

Weight

Container

CHANGES

PRICE ADVICE

Price

Effective Date

SENDS

FROM

FOR

REQUISITION

Item Number

Qty Requested

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 customers

To manufacture assemblies the company

creates a sequence of processes (steps)

Each process is supervised by a department

Assume there are three type of processes:

PAINT, FIT, CUT

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Job-Shop Accounting System 2/4

During manufacturing an assembly could

pass through any sequence of processes, in

any order; it may pass through the same

process more than once

A unique Job# is given to any new

assembly.

Costs and started-terminated dates must be

recorded

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Job-Shop Accounting System 3/4

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 4/4

CUSTOMER

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 Type

Machine Type

FIT PROC

Fit Proc ID

Fit Type

PAINT PROC

Paint Proc ID

Paint Method