EXCEPT (MINUS) for differences in SQL - Mini Project: Build & Apply

Find Unique Customers Using EXCEPT

📖 Scenario: You work for a retail company that has two sales regions: East and West. Each region has a list of customers who made purchases. You want to find customers who bought from the East region but not from the West region.

🎯 Goal: Build an SQL query using EXCEPT to find customers who purchased only in the East region and not in the West region.

📋 What You'll Learn

Create a table called east_customers with a single column customer_name and insert these exact customers: 'Alice', 'Bob', 'Charlie'

Create a table called west_customers with a single column customer_name and insert these exact customers: 'Bob', 'Diana'

Write a query using EXCEPT to select customers from east_customers who are not in west_customers

💡 Why This Matters

🌍 Real World

Retail companies often need to compare customer lists from different regions or time periods to find unique customers or changes in buying patterns.

💼 Career

Knowing how to use EXCEPT or MINUS helps database analysts and developers write queries that compare datasets efficiently, a common task in data analysis and reporting.

1

Create the east_customers table and insert data

Create a table called east_customers with one column customer_name of type VARCHAR(50). Insert these exact customers: 'Alice', 'Bob', and 'Charlie'.

SQL

-- Create east_customers table and insert customers
-- Your code here

Need a hint?

Use CREATE TABLE to make the table and INSERT INTO with multiple VALUES to add customers.

2

Create the west_customers table and insert data

Create a table called west_customers with one column customer_name of type VARCHAR(50). Insert these exact customers: 'Bob' and 'Diana'.

SQL

-- Create west_customers table and insert customers
-- Your code here

Need a hint?

Repeat the table creation and insertion steps for the west_customers table.

3

Write the EXCEPT query to find unique East customers

Write an SQL query that selects customer_name from east_customers except those in west_customers. Use EXCEPT to find customers who bought only in the East region.

SQL

-- Write the EXCEPT query to find customers in east_customers but not in west_customers
-- Your code here

Need a hint?

Use SELECT from both tables and connect them with EXCEPT to get the difference.

4

Complete the query with ordering

Add an ORDER BY customer_name clause at the end of your EXCEPT query to list the unique East customers alphabetically.

SQL

-- Add ORDER BY clause to sort the results alphabetically
-- Your code here

Need a hint?

Use ORDER BY customer_name after the EXCEPT query to sort the output.