Retreive Column names from the selected table using Dropdown

Hi Team,

I have a requirement that I need to list down all the columns from a selected table in the Drop Down input. 

  a Select Dynamic Column names based on the selected table name

For listing down all the table names from the database, i have used "External Source " option of Dropdown toolbox. 

But I am unable to get how to select column names from the selected table name using another dropdown. 

I need to get list of all columns from the selected table from the dropdown option. 

Kindly let me know if there is any other way to do it.