3.2. GROUP BY & HAVING

Try these first

1. 1.

   Write an SQL query to count the number of products sold in each category.

   Hint

   Remember to use GROUP BY after the SELECT statement.

2. 2.

   How would you find the total number of orders made by each customer?

   Hint

   You'll need to aggregate by customer ID.

3. 3.

   What clause do you use to group results based on a specific column?

   • HAVING
   • GROUP BY
   • ORDER BY

   Hint

   Think about how you would summarize data.

4. 4.

   True or False: The HAVING clause can be used without GROUP BY.

   • True
   • False

   Hint

   Remember what HAVING is designed for.

5. 5.

   Draft a SQL query that identifies the three products with the highest sales, excluding any product that sold less than 50 units.

   Hint

   Use GROUP BY and HAVING effectively to filter.

6. 6.

   Create a comprehensive report using SQL that highlights customer segments based on their number of purchases, categorizing them as 'Low', 'Medium', or 'High' based on thresholds you define.

   Hint

   You’ll need to use a CASE statement along with GROUP BY and HAVING.