MySQL ISNULL() Function

The ISNULL() function in MySQL checks if an expression evaluates to NULL (meaning it doesn't have a value). It's a simple but important function for handling missing data.

ISNULL(): Definition and Usage

This function is useful for conditional logic or data validation. It returns 1 if the expression is NULL, and 0 otherwise. It helps you to identify and handle situations where a value might be missing.

Syntax


ISNULL(expression)

Parameter Values

Parameter	Description
`expression`	The value or expression you want to check for `NULL`. This is required.

Examples

Testing a NULL Value

This checks if a NULL value is indeed NULL.

Syntax


SELECT ISNULL(NULL);

Output

Testing an Empty String

An empty string ("") is *not* considered NULL in MySQL.

Syntax


SELECT ISNULL("");

Output

Testing a Numeric Value

A numeric value is also not NULL.

Syntax


SELECT ISNULL(350);

Output

Testing a Non-Empty String

A non-empty string is not NULL.

Syntax


SELECT ISNULL("Hello world!");