Database Relations and Normal Forms

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What is the primary goal of relation decomposition?

To ensure each individual relation is in 2NF

To minimize the number of attributes in each relation

To ensure each individual relation is in BCNF or 3NF (correct)

To maximize the number of relations in the decomposition

What is the attribute preservation condition of a decomposition?

Each attribute in R appears in exactly two relation schemas Ri

Each attribute in R appears in at least one relation schema Ri (correct)

Each attribute in R appears in all relation schemas Ri

Each attribute in R appears in no relation schema Ri

Why is it not sufficient to consider individual relations in a decomposition to guarantee a good database design?

Because individual relations may not be in BCNF

Because the decomposition as a whole must be considered (correct)

Because individual relations may not be in 3NF

Because the number of relations in the decomposition is not sufficient

What is the purpose of specifying the set F of FDs that should hold on the attributes of R?

To make the FDs available to the design algorithms Signup and view all the answers

What is the dependency preservation condition of a decomposition?

FD X → Y can be inferred from the dependencies that appear in some Ri Signup and view all the answers

What is the result of decomposing the universal relation R into a set of relation schemas D?

A set of relations that together form the relational database Signup and view all the answers

What is the relation EMPLOYEE_3 based on?

Only tuples where Dnum is not NULL Signup and view all the answers

What is a challenge in normalization algorithms?

They are not always deterministic Signup and view all the answers

What is a multivalued dependency (MVD) in a relation schema?

A constraint on multiple tuples in a relation Signup and view all the answers

What is required to specify all the relevant dependencies among database attributes?

All functional dependencies Signup and view all the answers

What is the goal of normalization algorithms?

To achieve BCNF and preserve dependencies Signup and view all the answers

What is a trivial multivalued dependency (MVD)?

An MVD where Y is a subset of X or X υ Y is equal to R Signup and view all the answers

What is a functional dependency between two sets of attributes X and Y?

The value of X determines a unique value for Y Signup and view all the answers

What is the dependency preservation property in relational database design?

A decomposition that preserves all functional dependencies Signup and view all the answers

What is the purpose of finding the minimal cover of a set of functional dependencies?

To eliminate redundant dependencies Signup and view all the answers

What is the nonadditive (or lossless) join property in relational database design?

A decomposition that preserves data during join Signup and view all the answers

What is the purpose of the inference rules for functional dependencies?

To derive new functional dependencies Signup and view all the answers

What do functional dependencies represent in a relational database?

Real-world constraints on the attributes Signup and view all the answers