id      number NOT NULL PRIMARY KEY,
    name    varchar2(50)    NOT NULL,
    value   number NOT NULL,
    gmt_create  date NOT NULL DEFAULT sysdate,
    gmt_modified    date NOT NULL DEFAULT sysdate 
);
Query OK, 0 rows affected (0.06 sec)
obclient> INSERT INTO t_merge(id,name,value) values(1,'CN',1),(2,'US',2);
Records: 2  Duplicates: 0  Warnings: 0
obclient> MERGE INTO t_merge t2
 USING (SELECT id,name,value,gmt_create FROM t_insert ) t1
 ON (t2.id=t1.id)
 WHEN MATCHED THEN
     UPDATE SET t2.name=t1.name, t2.value=t1.value, t2.gmt_modified=sysdate
 WHEN NOT MATCHED THEN
     INSERT (t2.id,t2.name,t2.value) values(t1.id, t1.name, t1.value)
Query OK, 3 rows affected (0.01 sec)
obclient> select * from t_merge;  
+----+------+-------+---------------------+---------------------+
| ID | NAME | VALUE | GMT_CREATE          | GMT_MODIFIED        |
+----+------+-------+---------------------+---------------------+
|  1 | CN   | 10001 | 2020-04-02 17:51:59 | 2020-04-02 17:52:52 |
|  2 | US   | 10002 | 2020-04-02 17:51:59 | 2020-04-02 17:52:52 |
|  3 | EN   | 10003 | 2020-04-02 17:52:52 | 2020-04-02 17:52:52 |
3 rows in set (0.01 sec)