What will this query return? SELECT COUNT(*) FROM employees WHERE department = 'IT';

All employee records from the employees table

The total number of departments in the company

The number of employees working in the 'IT' department

The names of employees in the 'IT' department

medium #retrieving-data

QUESTION 01 OF 10

Retrieving Data

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Which clause filters rows before aggregation?

About this Quiz

This interactive assessment is designed to test your understanding of Retrieving Data. Whether you are a beginner looking to grasp the basics or an experienced professional aiming to refine your skills, quizzes are an excellent way to validate your knowledge and identify areas for improvement.

Instructions

Read each question carefully before answering.
Some questions may have multiple correct answers.
There is no time limit, so take your time to think.
You will receive immediate feedback after submission.

Learning Outcomes

Self-assess your current skill level.
Reinforce key concepts through active recall.
Identify knowledge gaps to focus your study.
Gain confidence in your technical expertise.
Reinforce memory and recall.

Questions in this quiz:

1. Which clause filters rows before aggregation?

HAVING
GROUP BY
WHERE
ORDER BY

2. What will this query return?<pre code="SELECT COUNT() FROM employees WHERE department = 'IT';" language="sql"><code class="language-sql">SELECT COUNT() FROM employees WHERE department = 'IT';</code></pre>

All employee records from the <code>employees</code> table
The total number of departments in the company
The number of employees working in the 'IT' department
The names of employees in the 'IT' department

3. Which rule is TRUE when using GROUP BY?

Any column can appear in SELECT
All SELECT columns must be aggregated
SELECT columns must be either aggregated or in GROUP BY
GROUP BY must always use COUNT

4. Which query correctly finds departments with more than 5 employees?

<pre code="SELECT department FROM employees WHERE COUNT(*) > 5;" language="sql"><code class="language-sql">SELECT department FROM employees WHERE COUNT(*) > 5;</code></pre>
<pre code="SELECT department FROM employees GROUP BY department HAVING COUNT(*) > 5;" language="sql"><code class="language-sql">SELECT department FROM employees GROUP BY department HAVING COUNT(*) > 5;</code></pre>
<pre code="SELECT department FROM employees GROUP BY department WHERE COUNT(*) > 5;" language="sql"><code class="language-sql">SELECT department FROM employees GROUP BY department WHERE COUNT(*) > 5;</code></pre>
<pre code="SELECT department FROM employees HAVING COUNT(*) > 5;" language="sql"><code class="language-sql">SELECT department FROM employees HAVING COUNT(*) > 5;</code></pre>

5. What does BETWEEN 50000 AND 80000 do?

Includes only 50000
Includes only 80000
Includes both 50000 and 80000
Excludes both values

6. Which clause is evaluated last in SQL execution order?

WHERE
GROUP BY
HAVING
ORDER BY

7. Which query gives top 3 highest paid employees?

Option 1
Option 2
Option 3
Option 4

8. What happens if you use WHERE AVG(salary) > 70000?

It works fine
It filters groups
SQL error
Returns wrong result

9. Which is the correct way to filter aggregated data?

WHERE
HAVING
ORDER BY
LIMIT

10. What will this query return?<pre code="SELECT department, COUNT() FROM employees GROUP BY department;" language="sql"><code class="language-sql">SELECT department, COUNT() FROM employees GROUP BY department;</code></pre>

One row per employee
One row per department
One row per salary
One row total