SQL • LESSON 30

NULL Handling with COALESCE

Learn how to replace NULL values with useful fallback values.

🔴 Advanced⏱ 3 Minutes⭐ 470 XP
🤔 THE QUESTION

What should we display when an employee's department value is NULL?

💡 WHAT IS IT?

COALESCE returns the first non-NULL value from the values provided to it.

🎯 WHAT IS IT USED FOR?

It is useful for replacing missing values with defaults, making reports easier to read, and preventing NULL values from producing confusing output.

💻 EXAMPLE
SELECT
name,
COALESCE(department, 'Not Assigned')
AS department
FROM employees;

Mission Brief

Practice using COALESCE to replace missing department values with a readable fallback.

Objectives

  • ✓ SELECT
  • ✓ COALESCE
  • ✓ NULL
  • ✓ Fallback values
  • ✓ Column aliases
🚀 Start Mission