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CSE 3241 Final Questions with 100% Actual correct
CSE 3241 Final Questions with 100% Actual correct
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CSE 3241 FinalSELECT - ANS-Selects all tuples that satisfy the selection condition from a relation
Union - ANS-Produces a relation that includes ALL of the tuples in two relations, if they are
union compatible
Natural Join - ANS-Produces all the combinations of tuples from two relations that satisfy only
equality conditions, but if two attributes have the same name, they do not have to be specified
PROJECT - ANS-Produces a new relation with only some of the attributes, and removes
duplicate tuples
Outer Join - ANS-Produces a relation with all of the tuples of one relation and also the matching
tuples of another relation
Difference - ANS-Produces a relation that includes all of the tuples in one relation, that are not
also in another relation, if they are union compatible
Intersection - ANS-Produces a relation that includes all of the tuples that are in BOTH of two
relations, if they are union compatible
Theta Join - ANS-Produces all combinations of tuples from two relations that satisfy the join
condition
Cartesian Product - ANS-Produces a relation that has all of the attributes, and all of the tuples in
all possible combinations, of two relations, even if they are not union compatible
Equijoin - ANS-Produces all the combinations of tuples from two relations that satisfy only
equality conditions
The unary relational operations are - ANS-SELECT, PROJECT, RENAME
The benefits of using the Three Schema Architecture - ANS-Change the physical disk storage
without changing conceptual schema, gives different users different views of the same data,
data independence
Types of attributes - ANS-Composite, multi-valued, atomic
Weak entities - ANS-Are related to specific entities by identifying relationships
,Ternary relationships - ANS-Can adequately be represented as a separate relation with an
artificial key
All are true about disjoint subclasses - ANS-An entity can be a member of at most one of the
subclasses of the specialization, a superclass can have partial participation in disjoint
subclasses, a superclass can have total participation in disjoint subclasses
A tuple is: - ANS-An ordered set of attributes
A key: - ANS-Is a superkey, can have more than one in a tuple, uniquely identifies a tuple
When mapping a regular entity to a relational model which of the following apply: - ANS-Every
simple attribute maps to an attribute of the relation
A primary key of a weak entity is composed of - ANS-Both Primary Key of the identifying entity
as a foreign key as the partial key
Binary 1 : 1 relationships are mapped to a relational model by: - ANS-A foreign key on the entity
that fully participates in the relationship
Inserting a NULL for the primary key of a tuple represents what kind of violation: - ANS-Entity
Constraint
Atomicity - ANS-the transaction should either be performed in its entirety or not performed at all
Consistency preservation - ANS-If a transaction is completely executed from beginning to end
without interference from other transactions, it should take the database from one consistent
state to another
Isolation - ANS-A transaction should appear as though it is being executed in isolation from
other transactions, even though many transactions are executing concurrently
Durability or permanency - ANS-The changes applied to the database by a committed
transaction must persist in the database; these changes must not be lost because of any failure
A relation schema R is in 2NF if every non-prime attribute A in R is functionally dependent (FD)
on the primary key - ANS-False.
Full functional dependency means FD Y --> Z where removal of any attribute from Z means the
FD does not hold any more - ANS-False.
A relation schema R is generalized in 3NF if when a FD X--> A holds in R, then X is a superkey
of R and A is a prime attribute of R - ANS-False.
, A relation where all attributes are atomic is always in 1NF - ANS-True.
A binary relation is in BCNF - ANS-True.
A Prime attribute must be a member of SOME CANDIDATE KEY - ANS-True.
Transitive functional dependency means FD X --> Z that can be derived from two FDs X-->Y
and Y-->Z - ANS-True.
A relation schema R is in 3NF if it is in 2NF AND no non-prime attribute in R is transitively
dependent on the primary key - ANS-True.
A BCNF relation is always in 3NF - ANS-True
X --> Y holds if whenever two tuples have the same value for X, they MUST HAVE the same
value for Y - ANS-True.
If a relation R is decomposed into {R1, R2, ..., Rn} and the decomposition is lossless then -
ANS-The natural join of R1, R2,...,Rn will have the same number of tuples as the original
relation R
The functional dependency {A} --> {B} for the relation schema R(A,B,C,D) implies that -
ANS-Any two tuples in R that have the same value for A must have the same value for B
Given the FDs, {A,B} --> {C,D,E} and {A} --> {E}, for relation schema R= (A,B,C,D,E) we can
infer the following: - ANS-{A,B} is a key for R
A table that displays data redundancies yields the following anomalies: - ANS-Update
anomalies, Insertion anomalies, Deletion anomalies
A table where every determinant is a candidate key is said to be in - ANS-BCNF
A relation schema R is in 3NF if - ANS-R satisfies 2NF and no nonprime attribute of R is
transitively dependent on the primary key
If {A,B} --> {C,D} is one FD that holds for the relation schema R(A,B,C,D), then - ANS-{A,B} is a
candidate key for R, No two tuples in R can have the same values for both A and B, {A,B} is a
primary key for R
Given only the relation schema Books(TITLE, AUTHOR, Year, Publisher), we can infer the
following FD: - ANS-Author, Title --> Publisher
If the following FDs, ({A} --> {B}, {B} --> {C}) hold for the database schema R(A,B) and S(B,C),
then the join of R and S will be - ANS-Lossless
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