Natural join and its risks in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to perform a natural join between tables employees and departments.

SQL

SELECT * FROM employees [1] departments;

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

ANATURAL JOIN

BINNER JOIN ON

CLEFT JOIN

DCROSS JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using INNER JOIN without ON clause causes syntax error.

Using CROSS JOIN returns all combinations, not matching rows.

The NATURAL JOIN keyword joins two tables based on all columns with the same names.

2fill in blank

medium

Complete the code to find all employees with their department names using natural join.

SQL

SELECT employee_name, department_name FROM employees [1] departments;

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

ALEFT JOIN ON employees.department_id = departments.department_id

BNATURAL JOIN

CRIGHT JOIN ON employees.department_id = departments.department_id

DFULL JOIN ON employees.department_id = departments.department_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using LEFT JOIN without ON clause causes error.

Using RIGHT JOIN or FULL JOIN when natural join is intended.

NATURAL JOIN automatically joins on columns with the same name, here department_id.

3fill in blank

hard

Fix the error in the natural join query that causes unexpected results due to extra common columns.

SQL

SELECT * FROM employees [1] departments;

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

ALEFT JOIN ON employees.department_id = departments.department_id

BNATURAL JOIN

CINNER JOIN ON employees.department_id = departments.department_id

DCROSS JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Continuing to use NATURAL JOIN without checking common columns.

Using CROSS JOIN which returns all combinations.

Using INNER JOIN ON with explicit condition avoids risks of natural join matching unintended columns.

4fill in blank

hard

Fill both blanks to create a safe join avoiding natural join risks and selecting employee and department names.

SQL

SELECT employees.employee_name, departments.department_name FROM employees [1] departments [2] employees.department_id = departments.department_id;

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

AINNER JOIN

BLEFT JOIN

CON

DUSING

Attempts:

3 left

💡 Hint

Common Mistakes

Using NATURAL JOIN instead of INNER JOIN.

Using USING keyword which can still cause issues if column names differ.

Using INNER JOIN with ON clause specifies the join condition clearly, avoiding natural join risks.

5fill in blank

hard

Fill all three blanks to write a query that joins employees and departments safely, selecting employee name, department name, and filtering by department location.

SQL

SELECT [1], [2] FROM employees [3] departments ON employees.department_id = departments.department_id WHERE departments.location = 'New York';

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

Aemployees.employee_name

Bdepartments.department_name

CINNER JOIN

DNATURAL JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using NATURAL JOIN which may join on unintended columns.

Selecting columns without table prefixes causing ambiguity.

This query uses INNER JOIN with explicit ON clause to safely join tables and selects the correct columns.