CS6400 - Exam 3
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 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 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
, 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 ANS; 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 ANS; An attribute, or combination of attributes, that uniquely identifies a row in a
relation.
primary key ANS; A field (or group of fields) that uniquely identifies a given entity in a table
prime attribute ANS; A key attribute; that is, an attribute that is part of a key or is the whole key.
nonprime attribute ANS; An attribute that is not part of a key.
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 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 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
, 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 ANS; 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 ANS; An attribute, or combination of attributes, that uniquely identifies a row in a
relation.
primary key ANS; A field (or group of fields) that uniquely identifies a given entity in a table
prime attribute ANS; A key attribute; that is, an attribute that is part of a key or is the whole key.
nonprime attribute ANS; An attribute that is not part of a key.
