Mock Exam

Question 1

Which statement links with the following clauses?

WHERE
GROUP BY
HAVING
SELECT
FORM

Answer 1

WHERE - filters the rows (before aggregation)
GROUP BY - determines how aggregate functions are evaluated
HAVING - filters the rows (after aggregation)
SELECT - determines which columns appear
FROM - determines which tables are searched

Question 2

Give a true statement of a composite key?

Answer 2

It should improve the performance of some SELECT queries.

Question 3

What design is database vendor dependent?

Answer 3

Physical Design

Question 4

What is a main role for a database administrator?

Answer 4

Ensuring that the database is backed up regularly

Question 5

Do all tables need to have a foreign key?

Answer 5

No

Question 6

What do foreign keys ensure?

Answer 6

referential integrity

Question 7

Can a foreign key be NULL?

Answer 7

Yes

Question 8

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

Answer 8

Equi Join

Question 9

What is the term for a mapping from the members of one set to the members of a second set?

Answer 9

Relation

Question 10

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

Answer 10

0..*

Question 11

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

Eliminate partial key dependencies:

Answer 11

Second Normal Form

Question 12

State 3 points regarding optionality?

Answer 12

It specifies whether participation in the relationship is mandatory for a particular entity type or not

It is represented by the left-hand number in a multiplicity label

It is the minimum number of entities of a particular type that can participate in the relationship

Question 13

Select the true statement about the multiplicity label shown:

0..1

Answer 13

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

Question 14

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

Answer 14

Cardinality

Question 15

Select the category relevant to the action of allowing user X to insert records into table T

Answer 15

Access control

Question 16

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

Answer 16

aggregate

Question 17

What is Scalability in terms of NoSQL?

Answer 17

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

Question 18

Relational Databases are so called because…

Answer 18

The main data structure used is a relation.

Question 19

Using a transaction log reduces database performance - true or false?

Answer 19

True

Question 20

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

Answer 20

Serializability

Question 21

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

Answer 21

Data independence.

Question 22

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

Answer 22

Shared