DBMS Theory Quiz 2

Consider a relation R(A, B, C, D) with the following functional dependencies:
A → (B, C, D), (A, D) → (B, C) and (C, D) → (A, B). Identify the candidate key(s).

• {A}

• {A}, {C, D}

• {A}, {C, D}, {A, D}

• {C, D}

To achieve a lossless decomposition of a relation, what additional condition must be met when decomposing a relation into two or more smaller relations?

• The decomposed relations must have a common attribute.

• The decomposed relations must have no common attribute.

• The decomposed relations must have the same primary key.

• The decomposed relations must have the same candidate key.

The primary purpose of finding the canonical cover for a set of functional dependencies is to:

• To minimize redundancy in a relation

• To identify candidate keys

• To ensure 3NF compliance

• To simplify the functional dependency set

In which normal form do you address the issue of multivalued dependencies?

• 2NF

• 3NF

• 4NF

• 5NF

In a relational schema R (A, B, C) with functional dependencies A --> B, B --> C, and A --> C, which of the functional dependencies is redundant?

• A --> C

• A --> B

• B --> C

• None of the above

If DNo --> {DName, DLoc},

which of the following Armstrong's axioms allow the functional dependency DNo --> DName ?

• Reflexivity rule

• Augmentation rule

• Decomposition rule

• Union rule

For a decomposition of a relation to be "lossless", it actually means?

• No data is lost in the decomposition.

• The decomposition results in smaller relations.

• All attributes are preserved.

• It complies with 1NF.

When finding the canonical cover, what operation is used to eliminate extraneous dependencies?

• Union

• Intersection

• Decomposition

• Armstrong's Axioms

Assume a relation schema as R(A, B, C, D, E)

{A,B} is chosen as the Primary key for R.

Which of the following is true?

• A is non-key attribute

• C is non-prime attribute

• E is key attribute

• Insufficient data provided

If A→B, A→ C then which of the following is true?

• A→BC

• A→B

• A→C

• All of the mentioned