Chapter 6 HW

_______ means putting a relation into a higher normal form.

Normalization

If a relation is 3NF but not BCNF, it must have a non-trivial functional dependency X → A such that

X is not a superkey

We can ensure that a binary decomposition is lossless if the set of common attributes in the two relations is

a superkey of one of the relations

A relation is first normal form if

all of these

In relational decomposition of a universal relation, the property of dependency preservation requires that

all the attributes on both sides of each dependency appear in the same relation

The normalization process that starts with a universal relation and uses decomposition to produce a set of normalized relations is called

analysis

A relation is in first normal form (1NF) if, and only if

every attribute is single-valued for each tuple.

In relational decomposition of a universal relation, the property of attribute preservation requires that

every attribute of the universal relation appears in at least one relation

A relation is Boyce-Codd Normal Form if

every determinant is a superkey

A relation is second normal form if it is 1NF and

every nonkey attribute is dependent on the entire key

If X and Y are sets of attributes of relation R, we say that Y is functionally dependent on X if

for each X value there is only one Y value

If a relational decomposition is not lossless, doing joins to recreate the original table may produce a table that

has more rows than the original table

The standard decomposition algorithm for BCNF requires

identifying and removing each violation of BCNF from a universal relation

In the relational model, if A functional determines B, it means that

if two rows have the same A value, they must have the same B value

Which of the following is not one of the major objectives of normalization?

improving efficiency

In the relational model, a spurious tuple is one that

is created by a lossy join

It is always possible to find a Boyce-Codd Normal Form decomposition that

is lossless, but may not preserve dependencies

For a relational decomposition, the property of being able to get back exactly the original relation by joins is

lossless decomposition

A functional dependency is actually a _______ relationship from attribute set A to attribute set B.

many-to-one

A relation having only one candidate key is third normal form if it is 2NF and

no nonkey attribute is dependent on another nonkey attribute

If set S{A,B,C} is a candidate key for the relation R(A,B,C,D,E), then which of the following must be true

none of these

In the relational model, every determinant is always

none of these

In the relational model, all of the following are types of dependencies that have been shown to lead to update anomalies EXCEPT

simple

Using an E-R diagram can be helpful in designing a normalized schema because

standard mapping of an E-R diagram to a relational model results in a schema that is close to normalized

The normalization process in which we find and group together functional dependencies with the same determinant is called

synthesis

Examining an instance of a relation can be sufficient to prove

that is it not in 3NF

In the relational model, a projection is lossless if

the join produces the same tuples as the original relation

If a relation is 2NF but not 3NF, it must have which type of functional dependency?

transitive

A functional dependency in which the attributes on the right hand side are included in the determinant is called

trivial

If set S{A,B,C} is a superkey for the relation R(A,B,C,D,E), then

{A,B,C,D} is also a superkey for R

It is always possible to find a dependency preserving lossless decomposition for _______.

3NF

The highest normal form that always allows us to preserve functional dependencies is

3NF

In the relation R( A, B, C, D), having the composite key {A,B}, which of the following FDs would demonstrate that the relation is not 2NF?

A → C

In a relation R( A,B,C,D), which of the following would prove that R is not 3NF?

B → C

In the relation R( A, B, C, D), having the composite key {A,B}, which of the following FDs would demonstrate that the relation is not 3NF?

C → D

In the relation R(A,B,C,D) if D is multivalued and the apparent key is A, which of the following is NOT an acceptable way to create a first normal form table for this schema?

Decompose R into R1(A,B,C,D) and R2(D)

All of the following are reasons for leaving a schema in a lower normal form except

Desire to reduce replication