GROUP BY with aggregate functions in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the total sales for each product.

SQL

SELECT product_id, SUM([1]) FROM sales GROUP BY product_id;

Drag options to blanks, or click blank then click option'

Aquantity

Bprice

Cdiscount

Ddate

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a non-numeric column like 'date' causes errors.

Using 'price' sums prices, not quantities sold.

The SUM function adds up the values in the specified column. Here, we want to sum the quantity sold for each product.

2fill in blank

medium

Complete the code to count how many orders each customer made.

SQL

SELECT customer_id, COUNT([1]) FROM orders GROUP BY customer_id;

Drag options to blanks, or click blank then click option'

Acustomer_name

Btotal_amount

Corder_date

Dorder_id

Attempts:

3 left

💡 Hint

Common Mistakes

Counting 'customer_name' counts duplicates incorrectly.

Counting 'total_amount' might miss orders with null amounts.

The COUNT function counts the number of non-null values in the specified column. Counting order_id gives the number of orders per customer.

3fill in blank

hard

Fix the error in the query to find the average price per category.

SQL

SELECT category, AVG([1]) FROM products GROUP BY category;

Drag options to blanks, or click blank then click option'

Acategory

Bprice

Cproduct_name

Dstock

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-numeric column inside AVG causes errors.

Not grouping by category would cause incorrect results.

The AVG function calculates the average of numeric values. We must use the price column to get the average price per category.

4fill in blank

hard

Fill both blanks to find the maximum and minimum order amounts per customer.

SQL

SELECT customer_id, [1](order_amount), [2](order_amount) FROM orders GROUP BY customer_id;

Drag options to blanks, or click blank then click option'

AMAX

BMIN

CSUM

DCOUNT

Attempts:

3 left

💡 Hint

Common Mistakes

Using SUM or COUNT instead of MAX or MIN changes the meaning.

Mixing up MAX and MIN order.

MAX finds the highest value, and MIN finds the lowest value in a group. Here, they show the biggest and smallest order amounts per customer.

5fill in blank

hard

Fill all three blanks to find the average, total, and count of sales per region.

SQL

SELECT region, [1](sales_amount), [2](sales_amount), [3](sales_amount) FROM sales_data GROUP BY region;

Drag options to blanks, or click blank then click option'

AAVG

BSUM

CCOUNT

DMAX

Attempts:

3 left

💡 Hint

Common Mistakes

Using MAX instead of COUNT changes the meaning.

Mixing the order of aggregate functions.

AVG calculates the average sales, SUM adds all sales, and COUNT counts the number of sales entries per region.