Oracle merge

create table TEST_K
(
  C1 NVARCHAR2(100),
  C2 CLOB,
  C3 NVARCHAR2(100)
)

MERGE INTO test_k t1
USING (select 'abc' c1,'def' c3 from dual) t2
ON (t1.c1 = t2.c1)
WHEN MATCHED THEN
  UPDATE SET t1.c3 = t2.c3
WHEN NOT MATCHED THEN
  insert (t1.c1, t1.c3) values(t2.c1,t2.c3)