Lucas Mancini มีคำสั่งซื้อกี่รายการ?
How many orders does Lucas Mancini has?
invoices_df = pd.DataFrame(columns=['customer_id']); customers_df = pd.DataFrame(columns=['id', 'first_name', 'last_name'])
invoices_df[invoices_df['customer_id'].isin(customers_df[(customers_df['first_name'] == 'Lucas') & (customers_df['last_name'] == 'Mancini')]['id'])].count()