ifnull function
Applies to: 
Databricks SQL Databricks Runtime
Returns expr2 if expr1 is NULL, or expr1 otherwise. This function is a synonym for coalesce(expr1, expr2) with two arguments.
Syntax
ifnull(expr1, expr2)
Arguments
expr1: An expression of any type.expr2: An expression sharing a least common type withexpr1.
Returns
The result type is the least common type of expr1 and expr2.
Examples
SQL
> SELECT ifnull(NULL, array('2'));
[2]