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371. IS NULL

Learn how to identify rows where a column contains a NULL value.

📘 Lesson 371 of 728 ⏱ 8 min 🎯 Beginner

IS NULL checks whether a column or expression contains NULL, which represents a missing or unknown value.

NULL values are common in real-world datasets. Correctly identifying them is essential for accurate analysis and reporting.

Find employees whose manager information is missing.

SQL 
SELECT
    EmployeeName,
    ManagerID
FROM Employees
WHERE ManagerID IS NULL;

Analysts use IS NULL for data-quality checks, missing-value analysis, incomplete records, and exception reporting.

  • NULL represents a missing or unknown value.
  • Use IS NULL to find NULL values.
  • Do not use = NULL.
  • NULL is different from zero or an empty string.
  • NULL handling is important for accurate analysis.
How do you check for NULL in SQL?

Use the IS NULL condition.

Can you use = NULL?

No. NULL represents an unknown value, so IS NULL must be used.

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