input_file_name function
Applies to: 
Databricks SQL Databricks Runtime
Returns the name of the file being read, or empty string if not available.
This function is not available on Unity Catalog.
In Databricks SQL and Databricks Runtime 13.3 LTS and above this function is deprecated. Please use _metadata.file_name.
Syntax
input_file_name()
Arguments
This function takes no arguments.
Returns
A STRING.
If the information is not available an empty string is returned.
The function is non-deterministic.
Examples
> SELECT input_file_name();