Database Management System Questions and Answers

Q: A list consists of last names, first names, addresses and pin codes. If all people in the list have the same last name and same pin code a useful key would be

Correct answer: the compound key first name and last nameIf 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.

Q: A ______ module is typically designed so that it will run on a user workstation or personal computer.

Correct answer: ClientIn 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.

Q: Use of UNIQUE while defining an attribute of a table in SQL means that the attribute values are

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.

Q: The one guideline to be followed while designing the database is

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.

Q: The ______ language consists of SQL statements for operating on the data (insert, Modify, Delete) in tables that already exist.

Correct answer: Data ManipulationThe 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.

Q: Which of the following is a reason to model data?

Correct answer: All of the aboveA 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.

Q: Protection of data from unauthorized Disclosure results in loss of _______

Correct answer: ConfidentialityConfidentiality 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.

Q: Relations produced from an E-R model will always be

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.

Q: A data type or format is specified for each _________

Correct answer: DomainEach 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.

101.

A list consists of last names, first names, addresses and pin codes. If all people in the list have the same last name and same pin code a useful key would be

A.the pin code
B.the last name
C.the compound key first name and last name
D.the compound key last name and pin code

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.

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102.

A ______ module is typically designed so that it will run on a user workstation or personal computer.

A.Software
B.Server
C.Program
D.Client

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.

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103.

Use of UNIQUE while defining an attribute of a table in SQL means that the attribute values are

A.distinct values
B.cannot have NULL
C.both (A) & (B)
D.same as primary key

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.

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104.

The one guideline to be followed while designing the database is

A.A database design may be ambiguous.
B.It should avoid/reduce the redundancy.
C.Unrelated data should be in the same table so that updating the data will be easy.
D.An entity should not have attributes.

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.

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105.

The ______ language consists of SQL statements for operating on the data (insert, Modify, Delete) in tables that already exist.

A.Data Manipulation
B.Data Definition
C.Data Control
D.None

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.

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106.

Which of the following is a reason to model data?

A.Understand each user's perspective of data
B.Understand the data itself irrespective of the physical representation
C.Understand the use of data across application
D.All of the above

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.

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107.

Protection of data from unauthorized Disclosure results in loss of _______

A.Integrity
B.Availability
C.Confidentiality
D.Discretionary Security

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.

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108.

Relations produced from an E-R model will always be

A.First normal form.
B.Second normal form.
C.Third normal form.
D.Fourth normal form.

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.

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109.

Which one is true statement :

A.With finer degree of granularity of locking a high degree of concurrency is possible.
B.Locking prevents non-serializable schedules.
C.Locking cannot take place at field level.
D.An exclusive lock on data item X is granted even if a shared lock is already held on X.

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.

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110.

A data type or format is specified for each _________

A.Relation
B.Tuple
C.Database
D.Domain

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.

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