Database Management System Questions and Answers

Answer: C

Correct answer: the compound key first name and last name

If everyone shares the same last name and pin code, neither of those distinguishes anybody, so neither can be a key. Combining the first name with the last gives the only combination among the options that can vary from person to person.

Answer: D

Correct answer: Client

In client-server architecture the client runs on the user's own machine and handles the interface, while the server holds the data and does the shared work.

Answer: C

Correct answer: both (A) & (B)

In the SQL standard UNIQUE by itself permits nulls, but in the sense these questions use it - as the guarantee that the column identifies rows - it is taken to require distinct values and no nulls, which is what makes it equivalent in effect to a key.

Answer: B

Correct answer: It should avoid/reduce the redundancy.

Redundancy is the source of most update problems: the same fact stored twice can be changed in one place and not the other. Reducing it is what normalisation is for. The other three options each describe a fault rather than a guideline.

Answer: A

Correct answer: Data Manipulation

The Data Manipulation Language - SELECT, INSERT, UPDATE, DELETE - operates on the data in tables that already exist. Creating the tables themselves is the Data Definition Language's work.

Answer: D

Correct answer: All of the above

A data model serves all three purposes: it records how each user sees the data, it describes the data in its own right independently of any storage decision, and it shows how the same data is used across applications.

Answer: C

Correct answer: Confidentiality

Confidentiality is the property that data is disclosed only to those authorised to see it, so unauthorised disclosure is precisely its loss. Integrity concerns unauthorised change and availability unauthorised denial of access.

Answer: A

Correct answer: First normal form.

Mapping an E-R model produces tables whose entries are single atomic values, which is precisely first normal form. The higher normal forms depend on the functional dependencies among the attributes and are not guaranteed by the mapping.

Answer: A

Correct answer: With finer degree of granularity of locking a high degree of concurrency is possible

Locking a smaller unit - a row rather than a table - leaves more of the data free for other transactions, so concurrency rises; the cost is more locks to manage. The other statements are false: plain locking does not by itself prevent non-serializable schedules, field-level locking is possible, and an exclusive lock is refused while a shared lock is held.

Answer: B

Correct answer: Domain

Each attribute of a relation draws its values from a domain, and the data type or format is the specification of that domain. A tuple is a row and contains values of many different types.