ลูกค้าชื่อ "ทิลแมน เอิร์นเซอร์" ใช้ช่องทางการติดต่อใด?
Which contact channel has been used by the customer with name "Tillman Ernser"?
df_customers = pd.DataFrame(columns=['customer_id', 'customer_name']); df_customer_contact_channels = pd.DataFrame(columns=['customer_id'])
df_customer_contact_channels[df_customer_contact_channels['customer_id'].isin(df_customers[df_customers['customer_name']=='Tillman Ernser']['customer_id'])]['channel_code']