$ sqlplus user/pass
SQL*Plus: Release 9.2.0.6.0 - Production on Wed Aug 2 17:38:39 2006
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.6.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.6.0 - Production
SQL> select * from wwm2; --要更新的表
-------------------- ----------
222 222
111 111
ww'jj 111
llll 1111
dddd 2222
lllldf 111
lllldf 111
dsafdf 111
3435 111
ljjjjj 222
dsafdf 111
-------------------- ----------
3435 111
ljjjjj 222
SQL> select * from wwm5; --更新的條件表
-------------------- ----------
lllldf 111
test 9984
2 /
-------------------- ----------
111 111
ww'jj 111
lllldf 111
lllldf 111
dsafdf 111
3435 111
dsafdf 111
3435 111
SQL> update wwm2 set wwm2.town=(select wwm5.town from wwm5 where wwm5.id=wwm2.id)
2 /
-------------------- ----------
222
lllldf 111
lllldf 111
1111
2222
lllldf 111
lllldf 111
lllldf 111
lllldf 111
222
lllldf 111
-------------------- ----------
lllldf 111
222
13 rows selected.
SQL> update wwm2
2 set town=(select town from wwm5 where wwm5.id=wwm2.id)
3 where id=(select wwm5.id from wwm5 where wwm5.id=wwm2.id)
4 /
SQL> update wwm2
set town=(select town from wwm5 where wwm5.id=wwm2.id)
where exists (select 1 from wwm5 where wwm5.id=wwm2.id)
8 rows updated.
SQL> update (select a.town atown,a.id aid,b.town btown,b.id bid from wwm2 a,wwm5 b where a.id=b.id)
2 set atown=btown
3 /
set atown=btown
*
ERROR at line 2:
ORA-01779: cannot modify a column which maps to a non key-preserved table
SQL> /
2* set atown=btown
SQL> /
1 declare
2 cursor cur_wwm is select town,id from wwm5;
3 begin
4 for my_wwm in cur_wwm loop
5 update wwm2 set town=my_wwm.town
6 where id=my_wwm.id;
7 end loop;
8* end;
SQL> /
-------------------- ----------
222 222
lllldf 111
lllldf 111
llll 1111
dddd 2222
lllldf 111
lllldf 111
lllldf 111
lllldf 111
ljjjjj 222
lllldf 111
-------------------- ----------
lllldf 111
ljjjjj 222
1 merge into wwm2
2 using (select town,id from wwm5) b
3 on (wwm2.id=b.id)
4 when matched then update set town=b.town
5* when not matched then insert (town,id) values (null,null)
SQL> /
-------------------- ----------
---注意這個地方,被插入了一個空值.因爲WWM5的ID=9984在WWM2中不能匹配,根本原因是ORACLE9必須有WHEN NOT MATCHED子句,但是ORACLE10可以不許要,也就是ORACLE10可以不寫WHEN NOT MATCHED ,就不必插入NULL值了,爲解決這個問題,下一步會DELETE WWM5的ID=9984,這樣一來就不會執行WHEN NOT MATCHED
222 222
lllldf 111
lllldf 111
llll 1111
dddd 2222
lllldf 111
lllldf 111
lllldf 111
lllldf 111
ljjjjj 222
-------------------- ----------
lllldf 111
lllldf 111
ljjjjj 222
SQL> 2 using (select town,id from wwm5) b
SQL> 3 on (wwm2.id=b.id)
SQL> 4 when matched then update set town=b.town
SQL> 5* when not matched then insert (town,id) values (null,null)
SQL> /
來源:http://www.blogjava.net/Jhonney/archive/2010/06/25/324503.html