Mock Exam

Question 1

What does the HAVING clause do?

Answer 1

filters the rows (after aggregation)

Question 2

What does the SELECT line do?

Answer 2

determines which columns appear

Question 3

What does the FROM clause do?

Answer 3

determines which tables are searched

Question 4

What does the GROUP BY clause do?

Answer 4

determines how aggregate functions are evaluated

Question 5

What does the WHERE clause do?

Answer 5

filters the rows (before aggregation)

Question 6

What should a composite key index do?

Answer 6

It should improve the performance of some SELECT queries.

Question 7

Of the following options, which is Database Vendor Dependent:

1. Physical Design
2. The Data Dictionary
3. Logical Design
4. Normalisation

Answer 7

Physical Design

Question 8

What is an important part of a database administrator’s role

Answer 8

Ensuring that the database is backed up regularly.

Question 9

All tables must have a foreign key - True or False?

Answer 9

False

Question 10

Foreign Keys ensure referential integrity - True or False?

Answer 10

True

Question 11

What is the term for combining two relations based on values in one attribute in each relation being the same?

Answer 11

Equi-Join

Question 12

The label at the “child” end of an optional, one-to-many relationship should be:

Answer 12

0..*

Question 13

What is the stage of normalisation at which the following issue is addressed:

Eliminate partial key dependancies:

Answer 13

Second Normal Form

Question 14

Select the true statement about the multiplicity label shown:

0..1

Select one:

a. The entity is mandatory. The corresponding foreign key cannot be null.
b. The entity is optional. The corresponding foreign key cannot be null.
c. This is not a valid multiplicity label.
d. The entity is optional. The corresponding foreign key may be null.
e. The entity is mandatory. The corresponding foreign key may be null.

Answer 14

The entity is optional. The corresponding foreign key may be null.

Question 15

Each table should have exactly one Primary Key - True or False?

Answer 15

True

Question 16

What is the term for the maximum number of entities that can participate in a relationship?

Answer 16

Cardinality

Question 17

What does ‘Access Control’ allow a user to do?

Answer 17

allows user X to insert records into table T

Question 18

What is an appropriate response to an SQL injection attack

Answer 18

Inspect program code to ensure that SQL statements cannot be compromised.

Question 19

What part of SQL uses the ‘ON’ condition

Answer 19

JOIN

Question 20

What is the mongodb function that corresponds most closely to an SQL SELECT statement with a GROUP BY clause.

Answer 20

aggregate

Question 21

What is meant by Scalability in regards to NoSQL

Answer 21

NoSQL databases allow many machines to process a single query simultaneously.

Question 22

Relational Databases are so called because…

a. It is important to maintain good relations.
b. The main data structure used is a relation.
c. The database manages relations between entities.
d. Only related data can be stored in these databases.
e. All implementations are related.

Answer 22

b. The main data structure used is a relation.

Question 23

Using a transaction log reduces Database Performance - True or False?

Answer 23

True

Question 24

Which property of transactions is guaranteed by the two-phase locking strategy?

Answer 24

Serialisability

Question 25

What is the term for the conceptual separation of logical data from physically stored data?

Answer 25

Data Independence

Question 26

What is the term for a lock taken out by a read-only transaction?

Answer 26

Shared