ค้นหาชื่อของลูกค้าและพนักงานทั้งหมด
Find the names of all the customers and staff members.
df_staff = pd.DataFrame(columns = ['customer_details', 'staff_details'])
df_customers = pd.DataFrame(columns = ['customer_details', 'staff_details'])
pd.concat([df_staff['staff_details'], df_customers['customer_details']])