Regarding Combobox

Question

Hi,

I have combobox in windows form application i need to search items in my combobox dropdown items. I have feed the details to my sql database, and i need to call those details in my combo box. If I click on a detail like i have given department HR, admin, manager, if i click HR means, i need to get the list of HR who are in the list to my gridview. Kindly find a screenshot of my design below, if there is any suggestion, kindly let me know.