Table schema:
CREATE TABLE Services (Service_Type_Code VARCHAR); CREATE TABLE Ref_Service_Types (Service_Type_Description VARCHAR, Service_Type_Code VARCHAR)

Question: What is the description and code of the type of service that is performed the most often?
SQL: SELECT T1.Service_Type_Description, T1.Service_Type_Code FROM Ref_Service_Types AS T1 JOIN Services AS T2 ON T1.Service_Type_Code = T2.Service_Type_Code GROUP BY T1.Service_Type_Code ORDER BY COUNT(*) DESC LIMIT 1