MySQL ISNULL( ) Function

The MySQL ISNULL() function is used for checking whether an expression is NULL or not.

This function returns 1 if the expression passed is NULL; otherwise, it returns 0. The ISNULL() function in MySQL accepts the expression as a parameter and returns an integer with a value of a value 0 or 1 depending on the parameter passed.

MySQL ISNULL() function syntax is:

ISNULL(expression)

Parameters:

• expression – It is used to specify the expression.

Supported Versions of MySQL

The MySQL ISNULL function is supported on following versions:

• MySQL 5.7
• MySQL 5.6
• MySQL 5.5
• MySQL 5.1
• MySQL 5.0
• MySQL 4.1
• MySQL 4.0
• MySQL 3.23

Let’s look at some examples of the ISNULL() function in MySQL. Learning the ISNULL() function with examples will help in understanding the concept better.

Example 1

Implementing ISNULL() function.

SELECT ISNULL(NULL); 

Output:

1 

Example 2

Implementing ISNULL() function on a string.

SELECT ISNULL("gfg"); 

Output:

0 

Example 3

Implementing ISNULL() function on an integer value.

SELECT ISNULL(123); 

Output:

0 

• The ISNULL() function is used to check if a value is NULL or not.
• It returns 1 if the expression is NULL, otherwise it returns 0.
• It can be used in SELECT, WHERE, and other clauses.
• It is different from the IFNULL() function, which is the MySQL equivalent of SQL Server’s ISNULL().
• It is useful for handling NULL values in queries and filtering rows where a column is NULL or not NULL.