List all the service types.
select service_type_code from services
Which service code has successful details?
select t1.service_type_code from services as t1 join events as t2 on t1.service_id = t2.service_id where t2.event_details = 'Success'
Then which has both successful and failure event details?
select t1.service_type_code from services as t1 join events as t2 on t1.service_id = t2.service_id where t2.event_details = 'Success' intersect select t1.service_type_code from services as t1 join events as t2 on t1.service_id = t2.service_id where t2.event_details = 'Fail'