select * from t_temp 
 where not exists(
select cl1, cl2 
from t_original to, t_temp tt 
where to.cl1=tt.cl1 
and to.cl2=tt.cl2 )

------解决方案--------------------

insert into t_diff
select * from t_temp tt
  where not exists(
select tt.cl1, tt.cl2  
from t_original tor
where tor.cl1=tt.cl1  
and tor.cl2=tt.cl2 );

------解决方案--------------------
insert into t_diff
select a.cl1,b.cl2,b.cl3
from t_original a,t_temp b
where a.col1=b.col1 and a.col2<>b.col2

------解决方案--------------------
稍微改一下，参考而已：
SQL code

INSERT /*+append*/INTO t_diff NOLOGGING(cl1,cl2,cl3)
SELECT cl1,cl2,cl3 FROM t_temp t1
 WHERE not exists(
   SELECT /*+hash_aj*/1
    FROM t_original t2
     WHERE t1.cl1 = t2.cl1
     AND t1.cl2 = t2.cl2
);