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4. What is an addition anomaly in a database? Give an example.
5. Normalization is a systematic, step-by-step methodology. Describe how it is
such a methodology.
6. When is a relation not in the second normal form? Give an example. How
do you transform it into second normal form relations?
7. What are transitive dependencies in a relation? How do you remove transi-
tive dependencies?
8. What is the Boyce-Codd normal form (BCNF)? Under what condition is a
relation in BCNF?
9. What are multivalued dependencies? Explain with an example.
10. What is your understanding of the domain-key normal form? Why do you
think this normal form is the ultimate goal of good design of a proper rela-
tional data model?
EXERCISES
1. Indicate whether true or false:
A. Informal design of a relational data model starts with random tables
created intuitively.
B. Deletion anomaly prevents all deletion of data from a database.
C. Each normalization step removes only one type of irregularity.
D. When partial key dependencies are removed, a relation is in third normal
form.
E. In most cases, the first four normalization steps for fundamental normal
forms are sufficient to produce a truly relational data model.
F. A relation has transitive dependencies when every attribute is not func-
tionally dependent on the full primary key.
G. A relation in Boyce-Codd normal form is practically free from incorrect
functional dependencies.
H. If a data model is in fourth normal form, no multivalued dependencies
exist.
I. Join dependency in a relation is the same as multivalued dependency.
J. Decomposition of a relation into more than one relation is the general
technique in each step of the normalization process.
2. Describe the circumstances under which the normalization method is prefer-
able to the data model transformation method for creating a relational data
model. If you are the database designer for a florist business, which method
will you adopt? Why?
3. List the fundamental normal forms. Describe the type of irregularity each step
removes in arriving at the fundamental normal forms.
4. You are asked to create a small relational database to manage customer orders
for a small business manufacturing standard vacuum cleaner parts. Create and
initial data model through intuition for the Customer Order database. Nor-
malize the initial data model and produce the final relational data model.
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