nullif function
Applies to: 
Databricks SQL Databricks Runtime
Returns NULL if expr1 equals expr2, or expr1 otherwise.
Syntax
nullif(expr1, expr2)
Arguments
expr1: An expression of any type.expr2: An expression of the same type asexpr.
Returns
NULL if expr1 equals to expr2, or expr1 otherwise.
Examples
SQL
> SELECT nullif(2, 2);
NULL
> SELECT nullif(2, 3);
2