Database Design With Semantic Object Models Transformation of Semantic Objects into

Relational Database Designs Sample Objects

Seven Types of Semantic Objects

Simple ObjectsSingle relation. Fig. 7-2,1

Composite ObjectsOne relation for the object and another relation for each

multivalued attribute. The key of these relations is the composite of the identifier of the object plus the identifier of the group. Fig. 7-3,4

Compound ObjectsThe relationships (1:1, 1:N, N:M) between objects need to

be considered.

Semantic Objects Into Relations (Cont.) 1:1 Compound Objects

One relation is needed for each object. Relations are associated by placing the key of either relation as a foreign key in the other relation. Fig. 7-6,7

1:N and N:1 Compound ObjectsEach object is represented with a relation and the key of the

parent is place in the child. Fig. 7-8,9

N:M Compound ObjectsOne relation is needed for each object and a third one to be

the intersection relation. Fig. 7-10,11

Semantic Objects Into Relations (Cont.) Hybrid Objects

Transformed into relations using a combination of the techniques for composite and compound objects. Fig.7-12,13,14

Association ObjectsUse a relation for each of the three associated objects,

and then represent the relationships among the objects using the strategies used with compound objects. Fig. 7-15,16

Semantic Objects Into Relations (Cont.) Supertype (Parent) /Subtype Objects

Define a relation for the parent object and one for each of the subtype objects. The key of all these relations in the key of the parent. Fig. 7-17,18

Archetype/Version ObjectsThese are compound objects that model various

instances of the basic object e.g. releases of software products. Fig. 7-19,20

Sample Objects

Subscription Form -> Fig. 7-21 Product Description -> Fig. 7-22 Traffic-Warning Citation -> Fig. 7-23