NULLIF in MySQL

When the given two expressions are equal, the NULLIF() function compares them and returns NULL.

If not, the first expression is returned.

Examples:
SELECT NULLIF(34, 0);
Returns: 34

SELECT NULLIF(34, “SQL”);
Returns: 34

SELECT NULLIF(34, 34);
Returns: NULL

SELECT NULLIF(NULL, 34);
Returns: NULL (since it is the first expression)