Метрический плагин кода Visual Studio для C++

Используйте apply с case выражениями:

select v.agent, t.policy_ref, t.transaction_type, v.score
from #temptable t cross apply
     (values (opener, (case when t.opener = t.closer then 1.0 else 0.5 end)),
             (case when t.opener <> t.closer then t.closer end, 0.5)
     ) v(agent, score)
where v.agent is not null;

Или:

select v.agent, t.policy_ref, t.transaction_type,
       (case when t.opener = t.closer then 1.0 else 0.5 end) as score
from #temptable t cross apply
     (values (t.opener, 1),
             (t.closer, 2)
     ) v(agent, which)
where (t.opener <> t.closer) or (which = 1)