Worksheet MC

The term First Normal Form (1NF) describes the tabular format in which

(a) All the key attributes are defined (b) There are no repeating groups in the table. Row/column intersection can contain one and only one value, not a set of values (c) All attributes are dependent on the primary key

A table that displays data redundancies yields the following anomalies:

(a) Update anomalies (b) Insertion anomalies (c) Deletion anomalies

Given the set of functional dependencies, ({A, B} → {C, D, E} and {A} → {E}), for relation schema R = (A,B,C,D,E) we can infer the following:

(c) {A, B} is a key for R

A table where every attribute is fully functionally dependent on the key, is said to be in

2NF

The functional dependency {A} → {B} for relation schema R(A,B,C,D) implies that

Any two tuples in R that have the same value for A must have the same value for B

A relation schema R is in Second Normal Form (2NF) if every non-prime attribute A in R is functionally dependent (FD) on the primary key

F

A relation schema R is in generalized Third Normal Form (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

F

Full functional dependency means a FD Y → Z where removal of any attribute from Z means the FD does not hold any more

F

If the following functional dependencies, ({A} → {B}, {B} → {C}) hold for database schema R(A,B) and S(B,C), then the join of R and S will be

Lossless

A relation schema R is in 3rd Normal Form if

R satisfies 2nd Normal Form and no nonprime attribute of R is transitively dependent on the primary key

A Prime attribute must be a member of some candidate key

T

A relation schema R is in Third Normal Form (3NF) if it is in 2NF and no non-prime attribute in R is transitively dependent on the primary key

T

A relation where all attributes are atomic is always in 1st Normal Form

T

Transitive functional dependency means a FD X → Z that can be derived from two FDs X → Y and Y → Z

T

X → Y holds if whenever two tuples have the same value for X, they must have the same value for Y

T

If a relation R is decomposed into {R1, R2, ..., Rn} and the decomposition is lossless then

The natural join of R1, R2,..., Rn will have the same number of tuples as the original relation R