CS6400 - Exam 3 Questions With Correct
Answers
logical (or conceptual) level - CORRECT ANSWER✔✔-how users interpret the
| | | | | | | | | |
relation schemas and the meaning of their attributes
| | | | | | |
implementation (or physical storage) level - CORRECT ANSWER✔✔-how the
| | | | | | | | |
tuples in a base relation are stored and updated
| | | | | | | |
bottom-up design methodology - CORRECT ANSWER✔✔-(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 - CORRECT ANSWER✔✔-(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 - CORRECT
| | | | | | | | | | |
ANSWER✔✔-■ 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 - CORRECT ANSWER✔✔-refers to its meaning resulting
| | | | | | | | | | |
from the interpretation of attribute values in a tuple
| | | | | | | |
update anomalies - CORRECT ANSWER✔✔-can be classified into insertion
| | | | | | | | |
anomalies, deletion anomalies, and modification anomalies
| | | | |
Insertion Anomalies - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-occur when a value for one attribute
| | | | | | | | | |
that users wish to keep is unexpectedly removed when a value for another
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attribute is deleted | |
Modification Anomalies - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-Tuples generated by joining two
| | | | | | | | |
relations on attributes that are not keys or foreign keys on these relations.
| | | | | | | | | | | |
Waste of storage space - CORRECT ANSWER✔✔-due to NULLs and the difficulty
| | | | | | | | | | | |
of performing selections, aggregation operations, and joins due to NULL values
| | | | | | | | | |
A functional dependency (A->B) - CORRECT ANSWER✔✔-occurs when the
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attribute A uniquely determines B. A = left-hand side, B=right-hand-side.
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-is a property of the semantics or meaning of the attributes.
| | | | | | | | | |
,FD or f.d. - CORRECT ANSWER✔✔-abbreviation for functional dependency
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Candidate Key - CORRECT ANSWER✔✔-An attribute, or combination of attributes,
| | | | | | | | |
that uniquely identifies a row in a relation.
| | | | | | | |
legal relation states (or legal extensions) of R - CORRECT ANSWER✔✔-Relation
| | | | | | | | | | |
extensions r(R) that satisfy the functional dependency constraints
| | | | | | |
FD cannot be inferred automatically - CORRECT ANSWER✔✔-must be defined
| | | | | | | | | |
explicitly by someone who knows the semantics of the attributes of R.
| | | | | | | | | | |
diagrammatic notation - CORRECT ANSWER✔✔-isplaying FDs: Each FD is
| | | | | | | | |
displayed as a horizontal | | |
Normalization of Data - CORRECT ANSWER✔✔-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) - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-or lossless join property, guarantees
| | | | | | | | |
that the spurious tuple generation problem does not occur
| | | | | | | |
dependency preservation property - CORRECT ANSWER✔✔-ensures that each
| | | | | | | |
functional dependency is represented in some individual relation resulting after
| | | | | | | | | |
decomposition
superkey - CORRECT ANSWER✔✔-any key that uniquely identifies each row
| | | | | | | | |
key - CORRECT ANSWER✔✔-of a relation schema R = {A1, A2, ... , An} is a set of
| | | | | | | | | | | | | | | | | |
attributes S ⊆ R with the property that no two tuples t1 and t2 in any legal
| | | | | | | | | | | | | | | | |
relation state r of R will have t1[S] = t2[S].
| | | | | | | | |
Candidate Key - CORRECT ANSWER✔✔-An attribute, or combination of attributes,
| | | | | | | | |
that uniquely identifies a row in a relation.
| | | | | | | |
primary key - CORRECT ANSWER✔✔-A field (or group of fields) that uniquely
| | | | | | | | | | | |
identifies a given entity in a table
| | | | | |
prime attribute - CORRECT ANSWER✔✔-A key attribute; that is, an attribute that
| | | | | | | | | | | |
is part of a key or is the whole key.
| | | | | | | | |
nonprime attribute - CORRECT ANSWER✔✔-An attribute that is not part of a key.
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Answers
logical (or conceptual) level - CORRECT ANSWER✔✔-how users interpret the
| | | | | | | | | |
relation schemas and the meaning of their attributes
| | | | | | |
implementation (or physical storage) level - CORRECT ANSWER✔✔-how the
| | | | | | | | |
tuples in a base relation are stored and updated
| | | | | | | |
bottom-up design methodology - CORRECT ANSWER✔✔-(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 - CORRECT ANSWER✔✔-(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 - CORRECT
| | | | | | | | | | |
ANSWER✔✔-■ 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 - CORRECT ANSWER✔✔-refers to its meaning resulting
| | | | | | | | | | |
from the interpretation of attribute values in a tuple
| | | | | | | |
update anomalies - CORRECT ANSWER✔✔-can be classified into insertion
| | | | | | | | |
anomalies, deletion anomalies, and modification anomalies
| | | | |
Insertion Anomalies - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-Tuples generated by joining two
| | | | | | | | |
relations on attributes that are not keys or foreign keys on these relations.
| | | | | | | | | | | |
Waste of storage space - CORRECT ANSWER✔✔-due to NULLs and the difficulty
| | | | | | | | | | | |
of performing selections, aggregation operations, and joins due to NULL values
| | | | | | | | | |
A functional dependency (A->B) - CORRECT ANSWER✔✔-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. - CORRECT ANSWER✔✔-abbreviation for functional dependency
| | | | | | | |
Candidate Key - CORRECT ANSWER✔✔-An attribute, or combination of attributes,
| | | | | | | | |
that uniquely identifies a row in a relation.
| | | | | | | |
legal relation states (or legal extensions) of R - CORRECT ANSWER✔✔-Relation
| | | | | | | | | | |
extensions r(R) that satisfy the functional dependency constraints
| | | | | | |
FD cannot be inferred automatically - CORRECT ANSWER✔✔-must be defined
| | | | | | | | | |
explicitly by someone who knows the semantics of the attributes of R.
| | | | | | | | | | |
diagrammatic notation - CORRECT ANSWER✔✔-isplaying FDs: Each FD is
| | | | | | | | |
displayed as a horizontal | | |
Normalization of Data - CORRECT ANSWER✔✔-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) - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-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 - CORRECT ANSWER✔✔-or lossless join property, guarantees
| | | | | | | | |
that the spurious tuple generation problem does not occur
| | | | | | | |
dependency preservation property - CORRECT ANSWER✔✔-ensures that each
| | | | | | | |
functional dependency is represented in some individual relation resulting after
| | | | | | | | | |
decomposition
superkey - CORRECT ANSWER✔✔-any key that uniquely identifies each row
| | | | | | | | |
key - CORRECT ANSWER✔✔-of a relation schema R = {A1, A2, ... , An} is a set of
| | | | | | | | | | | | | | | | | |
attributes S ⊆ R with the property that no two tuples t1 and t2 in any legal
| | | | | | | | | | | | | | | | |
relation state r of R will have t1[S] = t2[S].
| | | | | | | | |
Candidate Key - CORRECT ANSWER✔✔-An attribute, or combination of attributes,
| | | | | | | | |
that uniquely identifies a row in a relation.
| | | | | | | |
primary key - CORRECT ANSWER✔✔-A field (or group of fields) that uniquely
| | | | | | | | | | | |
identifies a given entity in a table
| | | | | |
prime attribute - CORRECT ANSWER✔✔-A key attribute; that is, an attribute that
| | | | | | | | | | | |
is part of a key or is the whole key.
| | | | | | | | |
nonprime attribute - CORRECT ANSWER✔✔-An attribute that is not part of a key.
| | | | | | | | | | | |
