So, my teacher is an jerk, and threw this project at us without any examples. I'm not kidding. We just began SQL programming a week ago, and this particular project is giving me alot of headaches. I would appreciate any help.

3. Find the names of customers that have purchased items from two or more different employees, where the items have come from the same vendor.

4. Find the names of vendors that have had items sold by employees of only one department.

*** arf_department
DEPT_NO
DEPT_NAME

*** arf_customer
CUST_NO
CUST_NAME

*** arf_vendor
VENDOR_NO
VENDOR_NAME

*** arf_employee
DEPT_NO
EMP_NO
EMP_NAME

*** arf_inventory
VENDOR_NO
ITEM_CODE

*** arf_sales_transactions
EMP_NO
CUST_NO
ITEM_CODE