EXCEPT equivalent in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all customers who have placed orders but exclude those who have returned items.

MySQL

SELECT customer_id FROM orders WHERE status = 'placed' [1] SELECT customer_id FROM returns WHERE status = 'returned';

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

AMINUS

BINTERSECT

CUNION

DEXCEPT

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION instead of EXCEPT returns all rows from both queries.

Using INTERSECT returns only common rows, not the difference.

The EXCEPT keyword returns rows from the first query that are not in the second query. MySQL does not support EXCEPT directly, but this is the standard SQL syntax.

2fill in blank

medium

Complete the code to find products sold but not returned using a LEFT JOIN and filtering NULLs.

MySQL

SELECT p.product_id FROM products p LEFT JOIN returns r ON p.product_id = r.product_id WHERE r.product_id [1];

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

AIS NOT NULL

BIS NULL

C= NULL

D<> NULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using '= NULL' or '<> NULL' which are invalid in SQL.

Using IS NOT NULL which finds matched rows instead.

When using LEFT JOIN, rows from the left table without matches in the right table have NULLs. Filtering with IS NULL finds products not returned.

3fill in blank

hard

Fix the error in the query that tries to find employees who worked on projects but not on project 5.

MySQL

SELECT employee_id FROM project_assignments WHERE project_id != [1];

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

A5

BNULL

C'5'

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around numeric IDs causing type mismatch.

Using NULL with != which always returns false.

The query should exclude project 5 by using project_id != 5. Using NULL or quotes incorrectly causes errors or wrong results.

4fill in blank

hard

Fill both blanks to create a query that selects all students who took Math but not Science using NOT EXISTS.

MySQL

SELECT student_id FROM enrollments e1 WHERE course = [1] AND NOT EXISTS (SELECT 1 FROM enrollments e2 WHERE e2.student_id = e1.student_id AND course = [2]);

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

A'Math'

B'Science'

C'History'

D'English'

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the courses in the blanks.

Forgetting quotes around course names.

The query finds students enrolled in Math but excludes those also enrolled in Science using NOT EXISTS.

5fill in blank

hard

Fill all three blanks to write a query that lists all employees who are in the sales department but not in the marketing department using a subquery with NOT IN.

MySQL

SELECT employee_id FROM employees WHERE department = [1] AND employee_id NOT IN (SELECT employee_id FROM employees WHERE department = [2] AND status = [3]);

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

A'Sales'

B'Marketing'

C'Active'

D'Inactive'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong department names or missing quotes.

Not filtering by status in the subquery.

This query selects employees in Sales who are not in Marketing and have active status in the subquery.