Database: dog_kennels_minus_1_0
Question: Which owner has paid for the most treatments on his or her dogs? List the owner id and last name.
SQL: select t1.owner_id , t1.last_name from owners_dogs as t1 join treatments as t2 on t1.dog_id = t2.dog_id group by t1.owner_id order by count ( * ) desc limit 1