SQL Exercises

SQL INNER JOIN Exercises (With Answers)

12 Exercises
~60 min
8 Intermediate4 Advanced

Exercise 1

intermediate

Question

Join employees with their departments to show employee name and department name.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  department_id INT
);

CREATE TABLE departments (
  id INT PRIMARY KEY,
  name VARCHAR(100)
);
Show Solution

Solution

SQL
1SELECT e.name AS employee_name, d.name AS department_name
2FROM employees e
3INNER JOIN departments d ON e.department_id = d.id;

Expected Output

| employee_name | department_name |
|---|---|
| John | Sales |
| Jane | Engineering |

Explanation

INNER JOIN returns only rows that have matching values in both tables. Use table aliases (e, d) for cleaner code.

Exercise 1

intermediate

Question

Join employees with their departments to show employee name and department name.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  department_id INT
);

CREATE TABLE departments (
  id INT PRIMARY KEY,
  name VARCHAR(100)
);
Show Solution

Solution

SQL
1SELECT e.name AS employee_name, d.name AS department_name
2FROM employees e
3INNER JOIN departments d ON e.department_id = d.id;

Expected Output

| employee_name | department_name |
|---|---|
| John | Sales |
| Jane | Engineering |

Explanation

INNER JOIN returns only rows that have matching values in both tables. Use table aliases (e, d) for cleaner code.

Exercise 1

intermediate

Question

Join employees with their departments to show employee name and department name.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  department_id INT
);

CREATE TABLE departments (
  id INT PRIMARY KEY,
  name VARCHAR(100)
);
Show Solution

Solution

SQL
1SELECT e.name AS employee_name, d.name AS department_name
2FROM employees e
3INNER JOIN departments d ON e.department_id = d.id;

Expected Output

| employee_name | department_name |
|---|---|
| John | Sales |
| Jane | Engineering |

Explanation

INNER JOIN returns only rows that have matching values in both tables. Use table aliases (e, d) for cleaner code.

Exercise 1

intermediate

Question

Join employees with their departments to show employee name and department name.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  department_id INT
);

CREATE TABLE departments (
  id INT PRIMARY KEY,
  name VARCHAR(100)
);
Show Solution

Solution

SQL
1SELECT e.name AS employee_name, d.name AS department_name
2FROM employees e
3INNER JOIN departments d ON e.department_id = d.id;

Expected Output

| employee_name | department_name |
|---|---|
| John | Sales |
| Jane | Engineering |

Explanation

INNER JOIN returns only rows that have matching values in both tables. Use table aliases (e, d) for cleaner code.

Exercise 2

intermediate

Question

Find all orders with their customer names and product names.

Table Schema

SQL
CREATE TABLE customers (id INT, name VARCHAR(100));
CREATE TABLE products (id INT, name VARCHAR(100), price DECIMAL);
CREATE TABLE orders (id INT, customer_id INT, product_id INT, quantity INT);
Show Solution

Solution

SQL
1SELECT c.name AS customer, p.name AS product, o.quantity
2FROM orders o
3INNER JOIN customers c ON o.customer_id = c.id
4INNER JOIN products p ON o.product_id = p.id;

Expected Output

| customer | product | quantity |
|---|---|---|
| John | Laptop | 2 |
| Jane | Phone | 1 |

Explanation

You can chain multiple JOINs to connect several tables. Each JOIN adds one more table to the result.

Exercise 2

intermediate

Question

Find all orders with their customer names and product names.

Table Schema

SQL
CREATE TABLE customers (id INT, name VARCHAR(100));
CREATE TABLE products (id INT, name VARCHAR(100), price DECIMAL);
CREATE TABLE orders (id INT, customer_id INT, product_id INT, quantity INT);
Show Solution

Solution

SQL
1SELECT c.name AS customer, p.name AS product, o.quantity
2FROM orders o
3INNER JOIN customers c ON o.customer_id = c.id
4INNER JOIN products p ON o.product_id = p.id;

Expected Output

| customer | product | quantity |
|---|---|---|
| John | Laptop | 2 |
| Jane | Phone | 1 |

Explanation

You can chain multiple JOINs to connect several tables. Each JOIN adds one more table to the result.

Exercise 2

intermediate

Question

Find all orders with their customer names and product names.

Table Schema

SQL
CREATE TABLE customers (id INT, name VARCHAR(100));
CREATE TABLE products (id INT, name VARCHAR(100), price DECIMAL);
CREATE TABLE orders (id INT, customer_id INT, product_id INT, quantity INT);
Show Solution

Solution

SQL
1SELECT c.name AS customer, p.name AS product, o.quantity
2FROM orders o
3INNER JOIN customers c ON o.customer_id = c.id
4INNER JOIN products p ON o.product_id = p.id;

Expected Output

| customer | product | quantity |
|---|---|---|
| John | Laptop | 2 |
| Jane | Phone | 1 |

Explanation

You can chain multiple JOINs to connect several tables. Each JOIN adds one more table to the result.

Exercise 2

intermediate

Question

Find all orders with their customer names and product names.

Table Schema

SQL
CREATE TABLE customers (id INT, name VARCHAR(100));
CREATE TABLE products (id INT, name VARCHAR(100), price DECIMAL);
CREATE TABLE orders (id INT, customer_id INT, product_id INT, quantity INT);
Show Solution

Solution

SQL
1SELECT c.name AS customer, p.name AS product, o.quantity
2FROM orders o
3INNER JOIN customers c ON o.customer_id = c.id
4INNER JOIN products p ON o.product_id = p.id;

Expected Output

| customer | product | quantity |
|---|---|---|
| John | Laptop | 2 |
| Jane | Phone | 1 |

Explanation

You can chain multiple JOINs to connect several tables. Each JOIN adds one more table to the result.

Exercise 3

advanced

Question

List employees with their manager's name using a self-join.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  manager_id INT
);
Show Solution

Solution

SQL
1SELECT e.name AS employee, m.name AS manager
2FROM employees e
3INNER JOIN employees m ON e.manager_id = m.id;

Expected Output

| employee | manager |
|---|---|
| Jane | John |
| Bob | Jane |

Explanation

A self-join joins a table to itself. Use different aliases to distinguish between the two instances of the same table.

Exercise 3

advanced

Question

List employees with their manager's name using a self-join.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  manager_id INT
);
Show Solution

Solution

SQL
1SELECT e.name AS employee, m.name AS manager
2FROM employees e
3INNER JOIN employees m ON e.manager_id = m.id;

Expected Output

| employee | manager |
|---|---|
| Jane | John |
| Bob | Jane |

Explanation

A self-join joins a table to itself. Use different aliases to distinguish between the two instances of the same table.

Exercise 3

advanced

Question

List employees with their manager's name using a self-join.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  manager_id INT
);
Show Solution

Solution

SQL
1SELECT e.name AS employee, m.name AS manager
2FROM employees e
3INNER JOIN employees m ON e.manager_id = m.id;

Expected Output

| employee | manager |
|---|---|
| Jane | John |
| Bob | Jane |

Explanation

A self-join joins a table to itself. Use different aliases to distinguish between the two instances of the same table.

Exercise 3

advanced

Question

List employees with their manager's name using a self-join.

Table Schema

SQL
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  manager_id INT
);
Show Solution

Solution

SQL
1SELECT e.name AS employee, m.name AS manager
2FROM employees e
3INNER JOIN employees m ON e.manager_id = m.id;

Expected Output

| employee | manager |
|---|---|
| Jane | John |
| Bob | Jane |

Explanation

A self-join joins a table to itself. Use different aliases to distinguish between the two instances of the same table.

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