N5CS: Database Testing and Evaluation

What is one of the learning objectives for Database Testing and Evaluation?

• Evaluate your solution in terms of fitness for purpose and accuracy of output

• Understand the history of computer science

• Learn the basics of web design and development

• Master the principles of graphic design

Answer explanation

The learning objective for Database Testing and Evaluation is to evaluate your solution in terms of fitness for purpose and accuracy of output.

What is the purpose of testing SQL queries?

• To make them run faster

• To ensure they are fit for purpose and accurate

• To make them easier to write

• To reduce the size of the database

Answer explanation

To ensure they are fit for purpose and accurate

What does this SQL statement do?

SELECT *

FROM goalscorer

WHERE gtime > 70;

• It selects all players who scored in the first 70 minutes of a game

• It selects all players from the goalscorer table

• It selects all players who scored after the 70th minute of a game

• It updates the goalscorer table to only show goals after the 70th minute

Answer explanation

It selects all players who scored after the 70th minute of a game

Which players scored in the last 20 minutes of a game?

• Robert Lewandowski and Dimitris Salpingidis

• Alan Dzagoev and Roman Pavlyuchenko

• Václav Pilar and Theofanis Gekas

• Petr Jiráček and Václav Pilar

Answer explanation

The correct players who scored in the last 20 minutes of a game are Alan Dzagoev and Roman Pavlyuchenko.

What are the two criteria against which queries should be evaluated according to the text?

• Complexity and efficiency

• Fitness for purpose and accuracy of output

• Speed and reliability

• Length and clarity

Answer explanation

Queries should be evaluated based on their fitness for purpose and accuracy of output, as mentioned in the text.

What does "fitness for purpose" mean in the context of query evaluation?

• The solution must be the most efficient one available

• The solution must be complex and comprehensive

• The solution must be good enough to do the task required

• The solution must include additional data not asked for

Answer explanation

The solution must be good enough to do the task required

If a query's output includes additional columns not required but has the necessary information, how is it classified in terms of "fitness for purpose"?

• Not fit for purpose

• Fit for purpose but not accurate

• Fit for purpose

• Inaccurate and not fit for purpose

Answer explanation

If a query's output includes additional columns not required but has the necessary information, it is classified as 'Fit for purpose' because it provides the needed data despite the extra columns.

Which of the following is NOT a key question for evaluating the accuracy of output?

• Is everything included in the WHERE clause that is required?

• Are columns sorted correctly in ascending or descending order?

• Have linked tables been linked using the correct primary and foreign keys?

• Has the data been formatted in a specific font and size?

Answer explanation

The correct answer is 'Has the data been formatted in a specific font and size?' because it is not a key question for evaluating the accuracy of output, unlike the other options which focus on data integrity and correctness.

Why was the initial SQL statement considered not accurate?

• The 'matchid' column was not required.

• The 'gtime' values were incorrect.

• The 'player' names were listed in the wrong order.

• The 'teamid' was missing from the output.

Answer explanation

The 'matchid' column was not required because it was not relevant to the SQL statement.

Which SQL statement would produce this accurate result?

• SELECT teamid, player, gtime FROM goalscorer WHERE gtime > 70;

• SELECT matchid, teamid, player, gtime FROM goalscorer WHERE gtime > 70;

• SELECT teamid, player FROM goalscorer WHERE gtime > 70;

• SELECT * FROM goalscorer WHERE gtime > 70;

Answer explanation

The correct SQL statement is 'SELECT teamid, player, gtime FROM goalscorer WHERE gtime > 70;' as it retrieves the teamid, player, and gtime from the goalscorer table where gtime is greater than 70.