ค้นหารัฐที่ไม่มีพนักงานอยู่ในบันทึก
Find the states which do not have any employee in their record.
df = pd.DataFrame(columns = ['state_province_county', 'employee_address_id'])
df.loc[~df['state_province_county'].isin(df['employee_address_id']), 'state_province_county']