Oracle Fusion Middleware & Application Server

Thursday, December 31, 2009

Happy New Year

So, that's the last entry for this year.

Happy new year, guten Rutsch (german) and bonne et joyeuse année 2010 (french) to all my readers.

Next year I will continue with more stuff about Oracle Fusion Middleware 11g and Enterprise Content Management. So stay tune ... :-)

Wednesday, December 2, 2009

Fun with DUAL Table

Try this "little hack":

connect to Database as sysdba and execute following commands:

select * from dual;
D
-
X
select count(*) from dual;
COUNT(*)
--------
1
insert into dual values ('Y');
commit;

Connect in another session with a normal user and try to drop one table:
conn scott/tiger
drop table t1;
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-01422: exact fetch returns more than requested number of rows
select * from dual;
D
-
X

Cool the dual just shows one row as expected

Go back to the session with the connect as sysdba
select * from dual;
D
-
X

Upps, here is the same, one row in the dual.
create table copy_dual as select * from dual;
select * from copy_dual;
D
--
X
Y
And here we can see the two rows :-)
To clean up, just delete the second row in dual table
delete from dual where dummy = 'Y';
commit;
Addendum: Under Oracle 11.2.0.1.0 the error with the drop table command doesn't come up again