What is the payment method of Devin Mills.
SELECT DISTINCT t1.payment_method FROM customers AS t1 JOIN customer_contact_channels AS t2 ON t1.customer_id   =   t2.customer_id WHERE t1.customer_name  =  "Devin Mills"
payment method refers to payment_method; customer name is 'Devin Mills' refers to WHERE customer_name = 'Devin Mills'; DISTINCT is used to return unique values;