Advanced High Comp Databases

Question 1

What is the scope of a project?

Answer 1

The scope clarifies what the project must cover.

Question 2

What are the boundaries of a project?

Answer 2

The boundaries clarify what the project will not cover.

Question 3

What are the 4 things a project can be constrained by?

Answer 3

Time, Scope, Cost, Legal (compatibility with GDPR, etc)

Question 4

What are the 4 types of feasibility study?

Answer 4

Technical, Economic, Legal, Time

Question 5

When is a dashed line that points towards the dependent use case used in a Use Case Diagram?

Answer 5

This is when «include» is used to show a dependency between a Base Use Case & a Dependent Use Case.

Question 6

When is a dashed line that points toward the Base Use Case used in a Use Case Diagram?

Answer 6

This is when «extend» is used to show a dependency between a Base Use Case & a Dependent Use Case. Certain criteria must be met before this is actioned (ran).

Question 7

When is a dashed line used in an ER Diagram?

Answer 7

To show a weak relationship.

Question 8

When the end of a relationship is marked with a crossed line in an ER diagram, what does this mean?

Answer 8

Mandatory relationship: is required in the relationship.

Question 9

When the end of a relationship in an ER Diagram is marked with a circle, what does this mean?

Answer 9

Optional relationship: is optional in the relationship.

Question 10

What is a weak entity?

Answer 10

An entity that relies on an Owner Entity (entity that provides it with a foreign key) to create a primary key.

Question 11

What are the 5 new SQL datatypes?

Answer 11

VARCHAR (basically size), INTEGER(TINYINT, SMALLINT, MEDIUMINT, INT, BIGINT), FLOAT, DATE, TIME

Question 12

What is the HAVING clause used for in SELECT statements?

Answer 12

It’s used as a filter for groups of rows or aggregated data.

AKA: MIN, MAX, AVG, SUM, COUNT.

(Often used with the group by clause so that data is selected based on a specified condition)

Question 13

What does the NOT clause do?

Answer 13

Reverses or negates a condition in a query:

EG: NOT( name = “Mylo Turnbull”)

this will provide results where the name is not my name.

Question 14

What does the BETWEEN clause do?

Answer 14

Specify whether a value is within a range:

EG: WHERE number BETWEEN “5” AND “8”

Question 15

What does the IN clause do?

Answer 15

IN is used in replacement of the OR clause, to specify multiple values you want in the WHERE clause.

EG: WHERE number IN(1, 2, 3)

Question 16

What does the ANY operator do when used with a subquery?

Answer 16

It means return TRUE if the comparison is TRUE for any of the values in the subquery.

Question 17

What does the EXISTS operator do when used with a subquery?

Answer 17

A subquery will instead return a Boolean value of TRUE or FALSE.

If a subquery returns any rows, EXISTS will return TRUE, otherwise it will return FALSE.