Bogdan Shishedjiev Logical Data Model 1

Logical Data Model

How to convert to a rational model?

Bogdan Shishedjiev Logical Data Model 2

Entities

• Each entity class becomes a table with attributes the entity attributes. The primary key is the entity identifier or a special number

STUDENT

Name

LastName

Address

STUDENT

IDNumber

Name

LastName

Address

Bogdan Shishedjiev Logical Data Model 3

Binary Associations

• Cardinality x,1 – x,N

AUTHOR

NoAuthor

Name

BOOK

NoBook

BookName

NoAuthor

Bogdan Shishedjiev Logical Data Model 4

Binary Associations

• Cardinality x,1 – x,N

PERSON

Id

Name

CAR

CarId

Brand

Model

OwnerId

PurchaseData

Bogdan Shishedjiev Logical Data Model 5

Binary Associations

• Cardinality 0,1 – 1,1

CUSTOMER

CustID

Name

Address

MEMBERCARD

NoCard

IssueDate

OwnerID

Bogdan Shishedjiev Logical Data Model 6

Binary Associations

• Cardinality 0,1 – 0,1 or 1,1 – 1,1

STUDENT

StudID

Name

Name

Address

LOCKER

No

Volume

StudID

STUDENT

StudID

Name

Name

Address

LockNo

LOCKER

No

Volume

Bogdan Shishedjiev Logical Data Model 7

Binary Associations

• Cardinality x,N – x,N

STUDENT

StudID

Name

Name

Address

SUBJECT

SubjID

NameSubj

ENROLL

StudID

SubjID

Bogdan Shishedjiev Logical Data Model 8

Binary Associations

• Cardinality x,N – x,N

OWNER

OwnID

Name

RESTATE

EstID

address

OWNS

OwnID

EstjID

part

Bogdan Shishedjiev Logical Data Model 9

Ternary Association

TEACHER

TeachID

Name

SUBJECT

SubjID

NameSubj

LECTURE

TeachID

SubjID

RoomNo

Hours

ROOM

RoomNo

Places

Bogdan Shishedjiev Logical Data Model 10

Special Cases

• More than one association

PERSON

Id

Name

address

HOUSE

address

Postcode

OWN

OwnID

address

Bogdan Shishedjiev Logical Data Model 11

Special Cases

• Reflexive associations

PERSON

Id

Name

WifeId

Bogdan Shishedjiev Logical Data Model 12

Special Cases

• Reflexive associations

COMPANY

CompanyId

address

OWNS

MotherID

DaughterID

percentage

Bogdan Shishedjiev Logical Data Model 13

Weak Entity

APARTMENT

ApartNo

Address

Floor

BUILDING

Address

Bogdan Shishedjiev Logical Data Model 14

Subtypes

Article(ArticleId,Name,Price)

Keyboard(ArticleId,SerialID,NKeys,Producer)

CPU(ArticleId,brand,Freq,Cache)

Monitor(ArticleId,SerialID,screensize)

Bogdan Shishedjiev Logical Data Model 15

Historicizing

EMPLOYEE

EmpNo

Name

Job

Salary

Coefficient

JOBHISTORY

EmpNo

DateMod

newjob

Bogdan Shishedjiev Logical Data Model 16

Example

PRODUCT

ProductID

Name

ORDERN

OrdNo

Date

SupID

CONTAINS

ProductID

OrderNo

Quantity

SUPPLIER

SupID

Name

Bogdan Shishedjiev Logical Data Model 17

Exercise

Bogdan Shishedjiev Logical Data Model 18

Case Study - Policlinic

Bogdan Shishedjiev Logical Data Model 19

Case Study - Policlinic