UNIT IV Normalization

Normalisation is:

• Removing all necessary data from a database

• Organising a database to remove repeated entries and increase the accuracy of the data

• Putting fields from different tables into one big database

What is an atomic field?

• A field that contains multiple items of data

• A field that is repeated

• A field that contains only one item of data

What is a foreign key?

• A unique identifier in a database

• A primary key of one table that appears in another table

• A field that should not be in a table and needs removing

A table in ____ contains no transitive dependencies.

• 1NF

• 2NF

• 3NF

• none of the above

When is a table is said to be 3NF

• Normalization improves performance by reducing redundancy.

• If and only if it is in 2NF and every non key attribute is Non-transitively dependent on the primary key

• It involves introduction of redundancy in data

• None of the above

Identify the types of Data Anomalies:

• Add, Delete and Save anomalies

• Insert, Add and Save anomalies

• Update, Save and Insert anomalies

• Insert, Delete and Update anomalies

Which is the best example of a Primary Key?

• Price

• Name

• Address

• IC No

Consider the relation scheme R = {E, F, G, H, I, J, K, L, M, N} and the set of functional dependencies {{E, F} -> {G}, {F} -> {I, J}, {E, H} -> {K, L}, K -> {M}, L -> {N} on R. What is the key for R?

• {E, F}

• {E}

• {E, F, H}

• {E, F, H, K, L}

Relation R has eight attributes ABCDEFGH. F = {CH -> G, A -> BC, B -> CFH, E -> A, F -> EG} is a set of functional dependencies (FDs) so that F+ is exactly the set of FDs that hold for R. How many candidate keys does the relation R have?

• 5

• 3

• 4

• 6

In a schema with attributes A, B, C, D and E following set of functional dependencies are given

{A -> B, A -> C, CD -> E, B -> D, E -> A}

Which of the following functional dependencies is NOT implied by the above set? (Hint: use inference rules, Reflexive, Augmentations, Transitive)

• CD -> AC

• BC -> CD

• AC -> BC

• BD -> CD