在目标数据库建一张临时表

Create global temporary table test3 on commit preserve rows as select * from TEST1 ;

在目前数据库执行

insert into test3 select * from test1 where username='4444';

MERGE INTO TEST2 T1

USING (select * from test3) T2

ON ( T1.username=T2.username)

WHEN MATCHED THEN

UPDATE SET T1.password = T2.password where T1.username = T2.username

WHEN NOT MATCHED THEN

INSERT (T1.username,T1.password) VALUES(T2.username,T2.password);

commit;