ENTITY-RELATIONSHIP DATA MODEL - Database Design and Development: An Essential Guide for IT Professionals - page 228

Composite
Primary Key

LoanNo PDate

Address

PAmount

LoanNo

PmntNo

CustName Amount

CustNo

* repays PAYMENT

CUSTOMER borrows LOAN

*

*

1

* *

Primary
Key

Strong Entity Type

Identifying
Relationship

Weak Entity Type

Simple Attribute

Cardinality
Indicator

AcctNo

liaises

StfSSNo

Balance

*

1

opens ACCOUNT

1

STAFF manages

*

FstName

ISA

DepndNme

StfName

SAVINGS CHECKING

LstName

StfS rv ce

PhoneNo

Composite
Attribute

MidInitials

IntRate

StartDte Overdraft

Derived
Attribute

Multi-valued
Attribute

Figure 7-21 E-R data model: recapitulation of components and notations.

Primary Key
Single attribute
Composite

Relationship
Names
Cardinality indicators
Maximum
Minimum
Identifying and nonidentifying
Optional and mandatory conditions
Gerund

Sample ERD

Let us bring all the principles and concepts of E-R data modeling together and
create a data model for the information requirements for a university. Assume that
the data model has to represent only the teaching aspects of the university. Ignore
other information relating to receivables, payables, salaries, administration, employ-
ees, and so on.
Consider the following requirements to be included in the model: