LEFT JOIN in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all customers and their orders using a LEFT JOIN.

MySQL

SELECT customers.name, orders.order_id FROM customers [1] orders ON customers.id = orders.customer_id;

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

ALEFT JOIN

BINNER JOIN

CRIGHT JOIN

DFULL JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using INNER JOIN will exclude customers without orders.

RIGHT JOIN returns all orders even if no customer matches.

The LEFT JOIN returns all customers even if they have no orders.

2fill in blank

medium

Complete the code to get all employees and their department names, including employees without a department.

MySQL

SELECT employees.name, departments.name FROM employees [1] departments ON employees.dept_id = departments.id;

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

ARIGHT JOIN

BINNER JOIN

CCROSS JOIN

DLEFT JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using INNER JOIN excludes employees without departments.

RIGHT JOIN would include all departments, not all employees.

LEFT JOIN ensures all employees appear, even those without a department.

3fill in blank

hard

Fix the error in the LEFT JOIN query to include all products and their categories.

MySQL

SELECT products.name, categories.name FROM products [1] categories ON products.category_id = categories.id;

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

ARIGHT JOIN

BINNER JOIN

CLEFT JOIN

DFULL JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using INNER JOIN excludes products without categories.

FULL JOIN is not supported in MySQL.

LEFT JOIN returns all products, even those without a category.

4fill in blank

hard

Fill both blanks to select all students and their grades, including students without grades.

MySQL

SELECT students.name, grades.score FROM students [1] grades ON students.id [2] grades.student_id;

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ALEFT JOIN

B=

C!=

DRIGHT JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' in ON condition breaks the join logic.

RIGHT JOIN would keep all grades, not all students.

LEFT JOIN keeps all students, and the ON condition uses '=' to match student IDs.

5fill in blank

hard

Fill all three blanks to select all orders, their customers, and order dates, including orders without customers.

MySQL

SELECT orders.id, [1], orders.order_date FROM orders [2] customers ON orders.customer_id [3] customers.id;

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

Acustomers.name

BLEFT JOIN

C=

DINNER JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using INNER JOIN excludes orders without customers.

Using '!=' in ON condition breaks the join.

LEFT JOIN keeps all orders, matching customers by customer_id with '='.