MySQL Join Challenges - Practical Coding Exercises

Find Customers with Orders

Write a query using INNER JOIN to list customers who have placed orders.

Expected output: List of customer IDs and names with their order IDs.

Hint: Join customers and orders on customer_id.

List All Customers with Order Info

Write a query using LEFT JOIN to list all customers and their orders, including those without orders.

Expected output: All customers listed with order IDs or NULL if no orders.

Hint: Use LEFT JOIN from customers to orders.

Simulate FULL JOIN

Write a query to simulate FULL JOIN between customers and orders.

Expected output: All customers and orders matched or unmatched.

Hint: Combine LEFT JOIN and RIGHT JOIN with UNION.

INNER JOIN returns only rows with matching keys in both tables, while LEFT JOIN returns all rows from the left table and matched rows from the right table, filling with NULLs if no match exists.

Since MySQL does not support FULL JOIN directly, you can simulate it by combining LEFT JOIN and RIGHT JOIN results using UNION.

Explicit join conditions prevent Cartesian products, which can cause very large and incorrect result sets.