เอกสารที่มี ID 4 ส่งไปที่ที่อยู่ใด
What address was the document with id 4 mailed to?
df_addresses = pd.DataFrame(columns=['document_id', 'address_details']); df_mailed = pd.DataFrame(columns=['document_id', 'mailed_to_address_id'])
df_addresses[df_addresses['document_id'] == df_mailed[df_mailed['document_id'] == '4']['mailed_to_address_id'].values[0]]['address_details'].values[0]