วันที่วางคำสั่งซื้อที่มีหมายเลขใบแจ้งหนี้คือ 10 คือเมื่อใด
What is the placement date of the order whose invoice number is 10?
df_orders = pd.DataFrame(columns=['date_order_placed', 'order_id']); df_shipments = pd.DataFrame(columns=['order_id', 'invoice_number'])
df_orders.set_index('order_id').join(df_shipments.set_index('order_id'))[df_shipments['invoice_number'] == 10]['date_order_placed']