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List the advantages of flat,
relational and hierarchical databases.
For a small
number of cases, flat databases do a reasonably fast job. In a
relational database if Tables are appropriately
defined it is possible to avoid having to enter
missing information for variables that are not
logically possible. In a hierarchical
database, operations can be done on a number of
fields all at once as long as they belong to the
same class.
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Using the tables presented in
this lecture, what is the zip codes of the students
who got the grade of A. Describe, step by step,
which table you look up what datum you use to find
the answer to the question.
22101
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How does relational databases
avoid entering missing information for variables
which are logically missing.
Separate tables
reduces the need to collect information that is not
logically possible.
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