How many among them are with "success"?
SELECT count ( * )  FROM EVENTS AS T1 JOIN Services AS T2 ON T1.Service_ID   =   T2.Service_ID WHERE T2.Service_Type_Code   =  'Marriage' and Event_Details  =  'Success'
count of events = COUNT(*); with \"success\" refers to Event_Details = 'Success'; among them refers to joining EVENTS and Services tables on Service_ID;