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CS6400 - Exam 3 Questions with Detailed Verified Answers
logical (or conceptual) level
Ans: how users interpret the relation schemas and the meaning of their attributes
implementation (or physical storage) level
Ans: how the tuples in a base relation are stored and updated
bottom-up design methodology
Ans: (also called design by synthesis) considers the basic relationships among
individual attributes as the starting point and uses those to construct relation schemas
top-down design methodology
Ans: (also called design by analysis) starts with a number of groupings of attributes
into relations that exist together naturally
measures to determine the quality of relation schema design
Ans: ■ Making sure that the semantics of the attributes is clear in the schema
■ Reducing the redundant information in tuples
■ Reducing the NULL values in tuples
■ Disallowing the possibility of generating spurious tuples
semantics of a relation
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Ans: refers to its meaning resulting from the interpretation of attribute values in a
tuple
update anomalies
Ans: can be classified into insertion anomalies, deletion anomalies, and modification
anomalies
Insertion Anomalies
Ans: occur when users attempt to store an attribute value in the system but they
cannot because the value of another unnecessary but required attribute is not known
Deletion Anomalies
Ans: occur when a value for one attribute that users wish to keep is unexpectedly
removed when a value for another attribute is deleted
Modification Anomalies
Ans: occur when changes to multiple instances of an entity (rows of a table) are
needed to effect an update to a single value of an attribute
Spurious tuples
Ans: Tuples generated by joining two relations on attributes that are not keys or
foreign keys on these relations.
Waste of storage space
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Ans: due to NULLs and the difficulty of performing selections, aggregation operations,
and joins due to NULL values
A functional dependency (A->B)
Ans: occurs when the attribute A uniquely determines B. A = left-hand side, B=right-
hand-side.
-is a property of the semantics or meaning of the attributes.
FD or f.d.
Ans: abbreviation for functional dependency
Candidate Key
Ans: An attribute, or combination of attributes, that uniquely identifies a row in a
relation.
legal relation states (or legal extensions) of R
Ans: Relation extensions r(R) that satisfy the functional dependency constraints
FD cannot be inferred automatically
Ans: must be defined explicitly by someone who knows the semantics of the attributes
of R.
diagrammatic notation
Ans: isplaying FDs: Each FD is displayed as a horizontal
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Normalization of Data
Ans: a process of analyzing the given relation schemas based on their FDs and primary
keys to achieve the desirable properties of (1) minimizing redundancy and (2)
minimizing the insertion, deletion, and update anomalies
Boyce-Codd Normal Form (BCNF)
Ans: A special type of third normal form (3NF) in which every determinant is a
candidate key. A table in BCNF must be in 3NF.
normal form test
Ans: is decomposed into smaller relation schemas that contain a subset of the
attributes and meet the test that was otherwise not met by the original relation.
nonadditive join
Ans: or lossless join property, guarantees that the spurious tuple generation problem
does not occur
dependency preservation property
Ans: ensures that each functional dependency is represented in some individual
relation resulting after decomposition
superkey
Ans: any key that uniquely identifies each row
key
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CS6400 - Exam 3 Questions with Detailed Verified Answers
logical (or conceptual) level
Ans: how users interpret the relation schemas and the meaning of their attributes
implementation (or physical storage) level
Ans: how the tuples in a base relation are stored and updated
bottom-up design methodology
Ans: (also called design by synthesis) considers the basic relationships among
individual attributes as the starting point and uses those to construct relation schemas
top-down design methodology
Ans: (also called design by analysis) starts with a number of groupings of attributes
into relations that exist together naturally
measures to determine the quality of relation schema design
Ans: ■ Making sure that the semantics of the attributes is clear in the schema
■ Reducing the redundant information in tuples
■ Reducing the NULL values in tuples
■ Disallowing the possibility of generating spurious tuples
semantics of a relation
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,Click here for more: Scholars nexus
Ans: refers to its meaning resulting from the interpretation of attribute values in a
tuple
update anomalies
Ans: can be classified into insertion anomalies, deletion anomalies, and modification
anomalies
Insertion Anomalies
Ans: occur when users attempt to store an attribute value in the system but they
cannot because the value of another unnecessary but required attribute is not known
Deletion Anomalies
Ans: occur when a value for one attribute that users wish to keep is unexpectedly
removed when a value for another attribute is deleted
Modification Anomalies
Ans: occur when changes to multiple instances of an entity (rows of a table) are
needed to effect an update to a single value of an attribute
Spurious tuples
Ans: Tuples generated by joining two relations on attributes that are not keys or
foreign keys on these relations.
Waste of storage space
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,Click here for more: Scholars nexus
Ans: due to NULLs and the difficulty of performing selections, aggregation operations,
and joins due to NULL values
A functional dependency (A->B)
Ans: occurs when the attribute A uniquely determines B. A = left-hand side, B=right-
hand-side.
-is a property of the semantics or meaning of the attributes.
FD or f.d.
Ans: abbreviation for functional dependency
Candidate Key
Ans: An attribute, or combination of attributes, that uniquely identifies a row in a
relation.
legal relation states (or legal extensions) of R
Ans: Relation extensions r(R) that satisfy the functional dependency constraints
FD cannot be inferred automatically
Ans: must be defined explicitly by someone who knows the semantics of the attributes
of R.
diagrammatic notation
Ans: isplaying FDs: Each FD is displayed as a horizontal
© Get it right 2025 Getaway - Stuvia US All rights reserved
, Click here for more: Scholars nexus
Normalization of Data
Ans: a process of analyzing the given relation schemas based on their FDs and primary
keys to achieve the desirable properties of (1) minimizing redundancy and (2)
minimizing the insertion, deletion, and update anomalies
Boyce-Codd Normal Form (BCNF)
Ans: A special type of third normal form (3NF) in which every determinant is a
candidate key. A table in BCNF must be in 3NF.
normal form test
Ans: is decomposed into smaller relation schemas that contain a subset of the
attributes and meet the test that was otherwise not met by the original relation.
nonadditive join
Ans: or lossless join property, guarantees that the spurious tuple generation problem
does not occur
dependency preservation property
Ans: ensures that each functional dependency is represented in some individual
relation resulting after decomposition
superkey
Ans: any key that uniquely identifies each row
key
© Get it right 2025 Getaway - Stuvia US All rights reserved
