select
  service_name,                            -- SERVICE_NAME VARCHAR2(64)
  service_name_hash,                       -- SERVICE_NAME_HASH NUMBER
  wait_class_id,                           -- WAIT_CLASS_ID NUMBER
  wait_class#,                             -- WAIT_CLASS# NUMBER
  wait_class,                              -- WAIT_CLASS VARCHAR2(64)
  total_waits,                             -- TOTAL_WAITS NUMBER
  time_waited                              -- TIME_WAITED NUMBER
from
  gv$service_wait_class
where
  inst_id = USERENV('Instance')