User Activity

Create department field on incident table ,choices isITAmin2)create field as user -reference (sys_user)tableIf some one select department IT then all IT related uses are aviator in user field same like admin.how to write script for this scenario in S...
how to autopopulate the user values in the form when the form is loading by using display business rule in servicenow?
How to auto populate first name, and last name, when caller changed in incident form through script include in ServiceNow?