Database Reference
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8. What is an aggregate object? Give an example.
9. What is your understanding of total specialization? Explain with an example.
Do you think total specialization is common in data models?
10. Describe the notion of conceptual objects and physical objects with an
example.
EXERCISES
1. Indicate whether true or false:
A. The object-based data modeling technique produces generic models.
B. An identifier for an object set must not include more than three attributes.
C. Cardinality indicators denote the number of object sets that are in a rela-
tionship.
D. The maximum cardinality indicator denotes whether a relationship is
optional or mandatory.
E. The attributes of an object include only the intrinsic or inherent charac-
teristics of that object.
F. Two or more attributes of an object may share an attribute domain.
G. The many-to-many relationship is actually a one-to-many relationship
from either side of the relationship line.
H. Aggregate objects may have attributes but not relationships.
I. If some instances of the superset are not found in any of the subsets, then
this is partial specialization.
J. All recursive relationships are one-to-many relationships.
2. As a data modeler for a company manufacturing automobile parts, review any
one of the business processes in your company. Identify the objects, relation-
ships, and so on supporting this process. Create a partial data model diagram
showing these components.
3. You are a member of the database project team responsible for analyzing
information requirements for a grocery store and identifying the business
objects to be included in the data model. Describe how you will proceed with
your task. List the business objects you would identify.
4. Consider data modeling for an auction business. Customers in an auction busi-
ness fall into different categories. Consignors bring items for sale; buyers pur-
chase items at auction; property owners bring items for appraisal of values;
subscribers subscribe to auction catalogs. Can you apply the principles of gen-
eralization/specialization to customers in this business? If so, describe the
superset and the subsets. If not, explain the reasons.
5. You are a Senior Data Modeler for a local bank. Create a data model to cover
the major banking operations. State your assumptions on the types of
processes included in your data model.
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