3.1. COUNT, SUM, AVG, MAX, MIN

Try these first

1. 1.

   What SQL function would you use to count the number of users?

   Hint

   Think of how we track the number of entries in a dataset.

2. 2.

   How would you aggregate the total sales from a table?

   Hint

   Consider what you're adding up.

3. 3.

   What does the AVG function calculate?

   • Total of values
   • Lowest value
   • Average of values

   Hint

   Think about how you would find the average score.

4. 4.

   True or False: The COUNT function can return 0 if no rows meet the condition.

   • True
   • False

   Hint

   Consider what happens when there are no results.

5. 5.

   Write a complex SQL query that retrieves departments with an average salary above the total average salary and shows the maximum salary within each department.

   Hint

   You'll need to use subqueries to compare average salaries.

6. 6.

   Using a sales data table, create a query to find products whose total sales exceed the average sales of all products and list them.

   Hint

   Think about how you would aggregate and compare the totals.