isnull function
Applies to: 
Databricks SQL Databricks Runtime
Returns true if expr is NULL. This function is a synonym for is null operator.
Syntax
isnull(expr)
Arguments
expr: An expression of any type.
Returns
A BOOLEAN.
If expr is a VARIANT result of a:
- JSON path expression with a valid path,
- parse_json function,
- variant_explode table-valued function, or
- variant_explode_outer table-valued function
the result is always false.
Use the is_variant_null function function to check if the VARIANT encoded value is NULL, or cast the VARIANT to a specific type and check if the result is NULL.
Examples
> SELECT isnull(1);
false
> SELECT isnull(NULL:INTEGER);
true
> SELECT isnull(parse_json('{"key": null}'):key);
false
> SELECT isnull(parse_json('{"key": null}'):key::STRING);
true
> SELECT isnull(parse_json('{"key": null}'):wrongkey);
true
> SELECT is_variant_null(parse_json('{"key": null}'):key);
true