COMPLETING THE LOGICAL DESIGN - Database Design and Development: An Essential Guide for IT Professionals - page 333

PDate

ODate

CAddr

PmntNo

PAmount

ONo

OAmt

CName

CNo

1

1

pays for

CUSTOMER places ORDER PAYMENT

* *

1 1

*

ProdID

SDate

ProdCost

contains

SHIPMENT

* *

SQty PRODUCT

*

1

1

GROWER

CHANNEL

ISA

GrwrID

GrwrName

FLOWER ARRANGEMENT

ChnlID

ChnlName

ArngeType

FlwrName

FlwrSize

Figure 11-5 ERD for florist business.

• Represent relationships in the conventional data model.
• Include the necessary rules and constraints in the conventional data model.
• Review conventional data model for completeness.

Representing Entities

Figure 11-6 illustrates the representation of entities in the relational data model for
the florist business. Note how each entity is represented by a relation or table in the
relational data model.

Representing Attributes

Figure 11-7 illustrates the representation of attributes in the relational data model
for the florist business. Note how the representation is done as columns for attrib-
utes. Also, observe how entity identifiers or primary keys are represented in the
tables.

Representing Relationships

Figure 11-8 illustrates the representation of relationships in the relational data
model for florist business. As you know, relationships are represented through
foreign keys in the relational data model. Note the foreign key columns in the
appropriate tables. CustNo is a foreign key column in the ORDER relation. Also,
observe the foreign key columns in the PAYMENT, SHIPMENT, FLOWER, and
ARRANGEMENT relations.