This guide is specifically for MySQL syntax.

SQL Query to Filter NULL Values

Handle NULL values using IS NULL, IS NOT NULL, and COALESCE.

Quick Answer

SELECT * FROM table WHERE column IS NULL;

Explanation

NULL represents unknown/missing data. Use IS NULL/IS NOT NULL for comparison (= NULL doesn't work). COALESCE returns the first non-NULL value.

Query Variants

Is Null

SELECT * FROM employees WHERE manager_id IS NULL;

Is Not Null

SELECT * FROM employees WHERE phone IS NOT NULL;

Coalesce

SELECT name, COALESCE(phone, 'No phone') as phone FROM employees;

Nullif

SELECT name, NULLIF(status, 'inactive') as active_status FROM users;

Pro Tips

• Never use = NULL, always use IS NULL
• COALESCE handles multiple fallback values
• NULL in calculations returns NULL

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MySQL-Specific Notes

This page covers MySQL syntax. Other databases may have different syntax for similar operations.