2002.08.29 - SLIDE 1IS 257 - Fall 2002 Database Design: Conceptual Model and ER Diagramming University of California, Berkeley School of Information Management

IS 257 - Fall 2002 2002.08.29 - SLIDE 1

Database Design: Conceptual Model and ER Diagramming

University of California, Berkeley

School of Information Management and Systems

SIMS 202: Information Organization and Retrieval

IS 257 - Fall 2002 2002.08.29 - SLIDE 2

Lecture Outline

• Review– Information Systems Planning– Information Systems Architecture– Information Engineering

• Database Design

• ER Diagrams

• Developing the Conceptual Model

IS 257 - Fall 2002 2002.08.29 - SLIDE 3

Lecture Outline


• Database Design

• ER Diagrams


IS 257 - Fall 2002 2002.08.29 - SLIDE 4

Review

• Information Systems Planning

• Information Systems Architecture

• Information Engineering

• Database Design

IS 257 - Fall 2002 2002.08.29 - SLIDE 5

Information Systems Architecture

• Zachman ISA Framework components– Data

• The “what” of the information system– Process

• The “how” of the information system– Network

• The “where” of the information system– People

• Who performs processes and are the source and receiver of data and information.

– Events and Points in time• When processes are performed

– Reasons• For events and rules that govern processing

IS 257 - Fall 2002 2002.08.29 - SLIDE 6

Information Engineering

• A formal methodology that is used to create and maintain information systems

• Starts with the Business Model and works in a Top-Down fashion to build supporting data models and process models for that business model

IS 257 - Fall 2002 2002.08.29 - SLIDE 7

Information Engineering

Planning

Design

Analysis

Implementation

IS 257 - Fall 2002 2002.08.29 - SLIDE 8

Lecture Outline


• Database Design

• ER Diagrams


IS 257 - Fall 2002 2002.08.29 - SLIDE 9

Database Design Process

ConceptualModel

LogicalModel

External Model

Conceptual requirements




Application 1

Application 1

Application 2 Application 3 Application 4

Application 2

Application 3

Application 4

External Model

External Model

External Model

Internal Model

IS 257 - Fall 2002 2002.08.29 - SLIDE 10

Stages in Database Design

• Requirements formulation and analysis

• Conceptual Design -- Conceptual Model

• Implementation Design -- Logical Model

• Physical Design --Physical Model

IS 257 - Fall 2002 2002.08.29 - SLIDE 11


• Requirements formulation and analysis– Purpose: Identify and describe the data that

are used by the organization– Results: Metadata identified, Data Dictionary,

Conceptual Model-- ER diagram

IS 257 - Fall 2002 2002.08.29 - SLIDE 12


• Requirements Formulation and analysis– Systems Analysis Process

• Examine all of the information sources used in existing applications

• Identify the characteristics of each data element– numeric– text– date/time– etc.

• Examine the tasks carried out using the information

• Examine results or reports created using the information

IS 257 - Fall 2002 2002.08.29 - SLIDE 13


• Conceptual Model– Merge the collective needs of all applications– Determine what Entities are being used

• Some object about which information is to maintained

– What are the Attributes of those entities?• Properties or characteristics of the entity• What attributes uniquely identify the entity

– What are the Relationships between entities• How the entities interact with each other?

IS 257 - Fall 2002 2002.08.29 - SLIDE 14


• Logical Model– How is each entity and relationship

represented in the Data Model of the DBMS• Hierarchic?• Network?• Relational?• Object-Oriented?

IS 257 - Fall 2002 2002.08.29 - SLIDE 15


• Physical (AKA Internal) Model– Choices of index file structure– Choices of data storage formats– Choices of disk layout

IS 257 - Fall 2002 2002.08.29 - SLIDE 16


• External Model– User views of the integrated database – Making the old (or updated) applications work

with the new database design

IS 257 - Fall 2002 2002.08.29 - SLIDE 17

Lecture Outline


• Database Design

• ER Diagrams


IS 257 - Fall 2002 2002.08.29 - SLIDE 18

Entity

• An Entity is an object in the real world (or even imaginary worlds) about which we want or need to maintain information– Persons (e.g.: customers in a business,

employees, authors)– Things (e.g.: purchase orders, meetings,

parts, companies)

Employee

IS 257 - Fall 2002 2002.08.29 - SLIDE 19

Attributes

• Attributes are the significant properties or characteristics of an entity that help identify it and provide the information needed to interact with it or use it. (This is the Metadata for the entities.)

Employee

Last

Middle

First

Name SSN

Age

Birthdate

Projects

IS 257 - Fall 2002 2002.08.29 - SLIDE 20

Relationships

• Relationships are the associations between entities. They can involve one or more entities and belong to particular relationship types

IS 257 - Fall 2002 2002.08.29 - SLIDE 21

Relationships

ClassAttendsStudent

PartSuppliesproject parts

Supplier

Project

IS 257 - Fall 2002 2002.08.29 - SLIDE 22

Types of Relationships

• Concerned only with cardinality of relationship

TruckAssignedEmployee

ProjectAssignedEmployee


1 1

n

n

1

m

Chen ER notation

IS 257 - Fall 2002 2002.08.29 - SLIDE 23

Other Notations




“Crow’s Foot”

IS 257 - Fall 2002 2002.08.29 - SLIDE 24

Other Notations




IDEFIX Notation

IS 257 - Fall 2002 2002.08.29 - SLIDE 25

More Complex Relationships

ProjectEvaluationEmployee

Manager

1/n/n

1/1/1

n/n/1

ProjectAssignedEmployee 4(2-10) 1

SSN ProjectDate

ManagesEmployee

Manages

Is Managed By

1

n

IS 257 - Fall 2002 2002.08.29 - SLIDE 26

Weak Entities

• Owe existence entirely to another entity

Order-lineContainsOrder

Invoice #

Part#

Rep#

QuantityInvoice#

IS 257 - Fall 2002 2002.08.29 - SLIDE 27

Supertype and Subtype Entities

ClerkIs one ofSales-rep

Invoice

Other

Employee

Sold

Manages

IS 257 - Fall 2002 2002.08.29 - SLIDE 28

Many to Many Relationships

Employee

ProjectIsAssigned

ProjectAssignment

Assigned

SSN

Proj#

SSN

Proj#Hours

IS 257 - Fall 2002 2002.08.29 - SLIDE 29

Lecture Outline


• Database Design

• ER Diagrams


IS 257 - Fall 2002 2002.08.29 - SLIDE 30

Developing a Conceptual Model

• Overall view of the database that integrates all the needed information discovered during the requirements analysis.

• Elements of the Conceptual Model are represented by diagrams, Entity-Relationship or ER Diagrams, that show the meanings and relationships of those elements independent of any particular database systems or implementation details.

• Can also be represented using other modeling tools (such as UML)

IS 257 - Fall 2002 2002.08.29 - SLIDE 31


• Building the Conceptual Model for the Diveshop database

• Names for the Diveshop company?

IS 257 - Fall 2002 2002.08.29 - SLIDE 32


• We will look at a small business -- a diveshop that offers diving adventure vacations

• Assume that we have done interviews with the business and found out the following information about the forms used and types of information kept in files and used for business operations...

IS 257 - Fall 2002 2002.08.29 - SLIDE 33

Primary Business Operations

• The shop takes orders from customers for dive vacations.

• It ships information about the dive vacation to the customers.

• It rents diving equipment for the divers going on the trips (these may include additional people other than the customer)

• It bills the customer for the vacation and for equipment rental or sales.

IS 257 - Fall 2002 2002.08.29 - SLIDE 34

Business Operations (cont.)

• It arranges sub-trips to particular dive sites at the primary location.

• It provides information about the features of various sites to help customers choose their destinations.– Features include sea life found at the location

and shipwrecks

IS 257 - Fall 2002 2002.08.29 - SLIDE 35


• Each dive order (or sale or trip) is on an invoice to one customer.– Invoices contain:

• Line items for each type of equipment ordered,• Total amount due for the invoice,• Customer information:

– Name, address, phone, credit card info.

• Information must be kept on inventory of dive equipment.

• There are multiple types of dive equipment:– The prices charged for sale or rental are

maintained.

IS 257 - Fall 2002 2002.08.29 - SLIDE 36


• Destination information includes:– Name of the destination– information about the location (accomodations,

night life, travel cost, average temperatures for different times of the year

• Destinations have associated dive sites.• Dive Sites have associated features

– Sea life – Shipwrecks

IS 257 - Fall 2002 2002.08.29 - SLIDE 37


• One record is kept for each order by a customer and will include the method of payment, total price, and location information. (I.e. Customers may have multiple orders)

• The company needs to know how an order is to be shipped.

• The shop has to keep track of what equipment is on-hand and when replacements or additional equipment is needed

IS 257 - Fall 2002 2002.08.29 - SLIDE 38

Entities

• Customer

• Dive Order

• Line item

• Shipping information

• Dive Equipment/ Stock/Inventory

• Dive Locations

• Dive Sites

• Sea Life

• Shipwrecks

IS 257 - Fall 2002 2002.08.29 - SLIDE 39

Diveshop Entities: DIVECUST

Name

Customer no

Street

State/ProvCityZIP/Postal

Code

Country

First Contact

PhoneDiveCust

IS 257 - Fall 2002 2002.08.29 - SLIDE 40

Diveshop Entities: DIVEORDS

CustomerNo

Order no

SaleDate

ShipVia

DestinationCCExpDate

CCNumber

PaymentMethodDiveOrds

No ofPeople

VacationCost

ReturnDate

DepartDate

IS 257 - Fall 2002 2002.08.29 - SLIDE 41

Diveshop Entities: DIVEITEM

Item no

Order no

Rental/Sale

Qty

Line Note

DiveItem

IS 257 - Fall 2002 2002.08.29 - SLIDE 42

Diveshop Entities: SHIPVIA

Ship Via

ShipCost

ShipVia

IS 257 - Fall 2002 2002.08.29 - SLIDE 43

Diveshop Entities: DiveStok

Description

Item No

EquipmentClass

ReorderPoint

On Hand Cost

SalePrice

DiveStokRentalPrice

IS 257 - Fall 2002 2002.08.29 - SLIDE 44

Diveshop Entities: DEST

Destinationname

Destination no

Avg Temp (F)

SpringTemp (F) Avg

Temp (C)Summer

Temp (C)

SummerTemp (F)

TravelCost

WinterTemp (C)

FallTemp (F)

FallTemp (C)Dest

WinterTemp (F)

Accommodations

Body ofWater

NightLife

SpringTemp (C)

IS 257 - Fall 2002 2002.08.29 - SLIDE 45

Diveshop Entities: SITES

Destinationno

Site no

Site Name

SiteNotes

SiteHighlight

DistanceFrom Town (M)

DistanceFrom Town (Km)

Skill Level

Visibility(ft)

Depth (m)

Depth (ft)Sites

Visibility (m)

Current

IS 257 - Fall 2002 2002.08.29 - SLIDE 46

Diveshop Entities: BIOSITE

SpeciesNo

SiteNo

BioSite

IS 257 - Fall 2002 2002.08.29 - SLIDE 47

Diveshop Entities: BIOLIFE

Category

Species no

CommonName

Length(cm)

SpeciesName

Length(in)

Notesexternal

GraphicexternalBioLife

IS 257 - Fall 2002 2002.08.29 - SLIDE 48

Diveshop Entities: SHIPWRCK

Site no

Ship Name

Category

InterestType Tonnage

Length (ft)

Beam(m)

Beam(ft)

Length(m)Shipwrck

Cause

Commentsexternal

DateSunk

Passengers/Crew

Graphicexternal

Survivors

Condition

IS 257 - Fall 2002 2002.08.29 - SLIDE 49

Functional areas

• Ordering

• Inventory

• Supplies

• Shipping

• Billing

• Location/Site Selection– We will concentrate on Ordering and

Location/Site Selection (these are joined tasks)

IS 257 - Fall 2002 2002.08.29 - SLIDE 50

Ordering

Orders(DIVORDS)

Customer(DIVECUST)

Customers place OrdersEach Order needs Customer information

IS 257 - Fall 2002 2002.08.29 - SLIDE 51

Ordering

DiveOrdsOrdersDiveCust

Customer No ship

ShipVia

Order No

Ship Via

DiveItem Repeatingattribute

Customer No

IS 257 - Fall 2002 2002.08.29 - SLIDE 52

Ordering Normalization

DiveCust Orders

Customer No

DiveOrds

Ship

ShipVia

Order No

Ship Via

DiveItemContains

Item No

QtyOrder No

Customer No

Rental/sale

IS 257 - Fall 2002 2002.08.29 - SLIDE 53

Details of DiveItem

DiveStokSuppliesSupplier

Company# Has

DiveItem

Item No

Item No

On Hand

Sale Price

Order No

m n

We’re ignoring this part...

IS 257 - Fall 2002 2002.08.29 - SLIDE 54

Ordering: Full ER

CustomerNo

ShipVia

DestShipVia

DiveStok

DiveItem

DiveOrds

DiveCust

CustomerNo

ShipVia

OrderNo

OrderNo

ItemNo

ItemNo

DestinationName

Destination

Destinationno 1

1

1

1

1n

n

n

n

n

IS 257 - Fall 2002 2002.08.29 - SLIDE 55

Location/Site Selection

DestGoing

to?DiveOrds

DestinationNo

DestinationName

Destination

IS 257 - Fall 2002 2002.08.29 - SLIDE 56

Destination/ Sites

Dest

Sites

DiveOrds

CustomerNo

OrderNo

DestinationName

DestinationSite No

Destinationno

Destinationno

1

1

n

n

IS 257 - Fall 2002 2002.08.29 - SLIDE 57

Sites and Sea Life 1

BioLife

Sites

Site NoDestination

no

Multiple occurrencesof sea life...

IS 257 - Fall 2002 2002.08.29 - SLIDE 58

Diveshop ER diagram: BioSite

SpeciesNo

SiteNo

BioSite

IS 257 - Fall 2002 2002.08.29 - SLIDE 59

Sites and Sea Life 2

Sites

BioSite

BioLifeSpeciesNo

Site No

Site No

Destinationno

SpeciesNo

1

1

n

n

IS 257 - Fall 2002 2002.08.29 - SLIDE 60

Sites and Shipwrecks

Sites

ShipWrck

Site NoDestination

no

Site No

1/n

1

IS 257 - Fall 2002 2002.08.29 - SLIDE 61

DiveShop ER DiagramCustomer

No

ShipVia

Dest

Sites

BioSite

ShipVia

ShipWrck

BioLife DiveStok

DiveItem

DiveOrds

DiveCust

CustomerNo

ShipVia

OrderNo

OrderNo

ItemNo

ItemNo

DestinationName

Destination

SpeciesNo

Site No

Destinationno

Site No

Destinationno

SpeciesNo

Site No

1

1

1

1

1

1

1/n

1

1n

n

n

n

n

n

n

n

1

IS 257 - Fall 2002 2002.08.29 - SLIDE 62

What must be calculated?

• Total price for equipment rental?

• Total price for equipment sale?

• Total price of an order?– Vacation price– Equipment (rental or sale)– Shipping

IS 257 - Fall 2002 2002.08.29 - SLIDE 63

What is Missing??

• Not really an “enterprise-wide” database– No personnel

• Sales people• Dive masters• Boat captains and crew• payroll

– Local arrangements• Dive Boats• Hotels

– Suppliers/Wholesalers for dive equipment• Orders for new/replacement equipment

– No history (only current or last order)

IS 257 - Fall 2002 2002.08.29 - SLIDE 64

Next Time

• TUESDAY: – More on UML database modeling– Designing the Logical Model

Documents

2002.08.29 - SLIDE 1IS 257 - Fall 2002 Database Design: Conceptual Model and ER Diagramming University of California, Berkeley School of Information Management