ค้นหาชื่อลูกค้าที่ไม่มีนโยบายเกี่ยวข้อง
Find the names of customers who have no policies associated.
df_customers = pd.DataFrame(columns = ['customer_id', 'customer_details']); df_policies = pd.DataFrame(columns = ['customer_id'])
result = df_customers.loc[~df_customers['customer_id'].isin(df_policies['customer_id']), 'customer_details']