Worksheet MC

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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


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