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2. Differentiate between a semantic data model and a conventional data model.
Define the terms.
3. Explain some of the critical issues of the model transformation method.
4. List any three components of an object-based data model and describe how
these are transformed into a relational data model.
5. List any two types of attributes. How are these transformed into the rela-
tional data model?
6. How is a composite instance identifier transformed into the relational data
model? Provide two examples.
7. Describe the transformation of a one-to-many relationship with an
example.
8. What is an intersection relation? When is it necessary? Give an example.
9. What is an identifying relationship? How is this transformed into the rela-
tional data model? Explain with an example.
10. What are supersets and subsets? Show the transformation of superset and
subsets into the relational data model with a very simple example.
EXERCISES
1. Match the columns:
1. intersection relation A. transformed into conventional
data model
2. model transformation method B. same primary key in transformed
relations
3. weak entity type C. relation
4. semantic data model D. relation columns
5. aggregate object set E. foreign key in either participating
relation
6. entity type F. two foreign keys
7. superset and subset G. mandatory relationship
8. one-to-one relationship H. good for large complex databases
9. foreign key not null I. relation with concatenated primary
key
10. composite attribute J. additional relation
2. As the database designer of the relational database system for an automobile
manufacturer, you have chosen the model transformation method to create
the relational data model. Write a note to your project manager, describing
the process and highlighting aspects of the method that would need special
attention.
3. Describe how mandatory and optional conditions in relationships are trans-
formed into the relational data model. Give specific examples.
4. Draw an ERD for a small farm market. Transform it into a relational data
model.
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