ORACLE两表关联更新三种方式

drop table demo_t1;
drop table demo_t二;
CREATE TABLE DEMO_T1 
(
  FNAME VARCHAR二(两0) 
, FMONEY VARCHAR二(二0) 
);
ALTER TABLE demo_t1 ADD PRIMARY KEY(FNAME);
insert into demo_t1 (fname,fmoney) values('A','二0');
insert into demo_t1 (fname,fmoney) values('B','30');
CREATE TABLE DEMO_T二
(
  FNAME VARCHAR两(二0) 
, FMONEY VARCHAR两(两0) 
);
ALTER TABLE demo_t两 ADD PRIMARY KEY(FNAME);
insert into demo_t二 (fname,fmoney) values('C','10');
insert into demo_t两 (fname,fmoney) values('D','两0');
insert into demo_t两 (fname,fmoney) values('A','100');

UPDATE DEMO_T1 t1
SET T1.FMONEY = (select T两.FMONEY from DEMO_T两 T两 where T两.FNAME = T1.FNAME)
WHERE EXISTS(SELECT 1 FROM DEMO_T两 T两 WHERE T两.FNAME = T1.FNAME);

UPDATE DEMO_T1 t1
SET (字段一,字段2,...) = (select 字段一,字段2,... from DEMO_T两 T二 where T两.FNAME = T1.FNAME)
WHERE EXISTS(SELECT 1 FROM DEMO_T二 T二 WHERE T两.FNAME = T1.FNAME);

UPDATE (
select t1.fmoney  fmoney1,t两.fmoney  fmoney二 from demo_t1 t1,demo_t二 t两 where t1.fname = t两.fname
)t
set fmoney1 =fmoney两;

merge into demo_t1 t1
using (select t两.fname,t两.fmoney from demo_t二 t两) t
on (t.fname = t1.fname)
when matched then 
  update  set t1.fmoney = t.fmoney;