Syntax
------

IS NULL

Description
-----------

Tests whether a value is NULL. See also NULL Values in MariaDB.

Examples
--------

SELECT 1 IS NULL, 0 IS NULL, NULL IS NULL;
+-----------+-----------+--------------+
| 1 IS NULL | 0 IS NULL | NULL IS NULL |
+-----------+-----------+--------------+
|         0 |         0 |            1 |
+-----------+-----------+--------------+

Compatibility
-------------

Some ODBC applications use the syntax auto_increment_field IS NOT NULL to find
the latest row that was inserted with an autogenerated key value. If your
applications need this, you can set the sql_auto_is_null variable to 1.

CREATE TABLE t1 (auto_increment_column INT NOT NULL AUTO_INCREMENT PRIMARY
KEY);
INSERT INTO t1 VALUES (NULL);
SELECT * FROM t1 WHERE auto_increment_column IS NULL;

+-----------------------+
| auto_increment_column |
+-----------------------+
|                     1 |
+-----------------------+

URL: https://mariadb.com/kb/en/is-null/