Database Reference
In-Depth Information
Traditionally, it has been widely accepted that for most databases, attainment of 3NF
is acceptable. This course recommends a minimum attainment of BCNF. Recall that as
stated earlier (in section 4.8), BCNF is really a refinement of 3NF, and the normalization
process can bypass 2NF and 3NF, and go straight to BCNF. In rare circumstances, it may
be required to proceed to 5NF or 6NF, which is the ultimate.
Normalization is a technique that must be mastered by database designers. It improves
with practice and experience, and ultimately becomes almost intuitive. As your mastery
of normalization improves, you will find that there is a corresponding improvement in
your ability to design and/or propose database systems for various software systems.
However, be aware that the converse is also true: failure to master fundamental principles
of database design will significantly impair one's ability to design quality software systems.
Notwithstanding this, be careful not to be antagonistic about your views, as informed as they
may be. In this regard, Figure 4-8 summarizes a practical experience of the author.
Figure 4-8. Database Quibbles almost got me in Trouble
4.13 Review Questions
1.
State the two fundamental integrity rules and explain their
significance.
2.
What is a foreign key? Illustrate using an appropriate example.
How should foreign keys be treated?
3.
Clarify the following: functional dependence; non-loss
decomposition; Heath's theorem. Provide examples that will
illustrate the significance of these terms.
4.
State the normal forms covered in this Chapter. For each
normal form, state it, explain in your own words what it
means, provide an example of a relation that conforms to it
and one that does not.
 
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