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ISA 245 Final Exam Study Guide With 100% Complete Solution
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ISA 245 Final Exam Study Guide With 100%Complete Solution 2024-2026
What is the problem of redundancy in database design and
why is it usually, but not always, a bad thing? - Correct
Answer-The problem of redundancy in database design is
undesirable because it causes problems with maintaining
consistency after updates. However, redundancy can lead to
performance improvements such as when redundancy can
be used in place of a join clause.
More normalized = more tables = slower queries
Define the three types of anomalies - Correct Answer-1.
Insertion anomaly - occurs when you are inserting
inconsistent information into a table. Need to make sure that
inserted data is consistent with existing rows.
2. Update anomaly - when you change existing information
incorrectly. Need to update all rows referring to the variable
attribute being updated.
3. Deletion anomaly - happens when you delete a record that
contains attributes that shouldn't have been deleted.
How does normalization reduce or eliminate redundancy
and the potential for data anomalies? - Correct Answer-
Normalization reduces or eliminates redundancy and
potential for data anomalies because it breaks the entities
down so that there is no data redundancy across the
database
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, Define deletion anomaly - Correct Answer-Occurs when you
delete a record that contains attributes that shouldn't have
been deleted
Define functional dependency - Correct Answer-Describes
how individual attributes are related
Define Insertion anomaly - Correct Answer-Occurs when
you enter information incorrectly into a table - need to make
sure that data is consistent with existing rows
Define Join - Correct Answer-Used when you need to obtain
information based on two related tables
Update anomaly - Correct Answer-Occurs when you change
existing information incorrectly - must update all rows
relating to the attribute being updated
What is functional dependency? - Correct Answer-A
functional dependency is a relationship between two
attributes, typically between a PK and other non-key
attributes. The relationship states that an attribute Y is
functionally dependent on an attribute X, if for every
existence of X, that value of X uniquely identifies every
existence of Y. The left side is the determinant and the right
side is the dependent.
What is a dependency diagram and what is the purpose of
creating one? - Correct Answer-A dependency diagram
illustrates the various dependencies that might exist in a
non-normalized table. The function of a dependency
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