[OracleRenegade]

Could anyone provide the simplest of working examples of an update to an Oracle 9i table 'dual' with one collumn of type varchar2 via a Java Swing form?

I am struggling to penetrate thin client but failing with Oracle - and the documentation is not helping....



Thanks for any help...



R.

[jwenting]

"dual" is a kinda metatable, it doesn't exist. Updates to it have no effect (if they are possible at all).
It's mainly used where a select statement is required but no table is needed (like 'select sysdate into l_current_date from dual;').

[OracleRenegade]

Hi,


update dual set dummy = 'p' - works quite nicely, actually - and the point of my request was I wanted the most extreme simple example of how to do an update against Oracle through a Swing form without getting hung up on the complexities that real world examples give - hence restricting my request to DUAL.

Originally Posted by jwenting

"dual" is a kinda metatable, it doesn't exist. Updates to it have no effect (if they are possible at all).
It's mainly used where a select statement is required but no table is needed (like 'select sysdate into l_current_date from dual;').

[jwenting]

maybe you can do it, but you won't get the result back again. DUAL is like /dev/null on Unix filesystems, it's a big black hole you can put things into that never come back.
You can however (unlike /dev/null) also pull anything out of it that never was put in.

[OracleRenegade]

I beg to differ -


select *
from dual;

update dual set dummy = 'Y';

commit;

select *
from dual;

update dual set dummy = 'X';

commit;
select *
from dual;

update dual set dummy = 'Y';

commit;

select *
from dual;

update dual set dummy = 'X';

commit;



This yields -


D
-
X
1 row selected.
1 row updated.
Commit complete.

D
-
Y
1 row selected.
1 row updated.
Commit complete.


So sure - we treat dual like it is something different, but it is really just another table...

DROP TABLE SYS.DUAL CASCADE CONSTRAINTS;

CREATE TABLE SYS.DUAL
(
DUMMY VARCHAR2(1 BYTE)
)
TABLESPACE SYSTEM
PCTUSED 40
PCTFREE 10
INITRANS 1
MAXTRANS 255
STORAGE (
INITIAL 16K
NEXT 16K
MINEXTENTS 1
MAXEXTENTS 505
PCTINCREASE 50
FREELISTS 1
FREELIST GROUPS 1
BUFFER_POOL DEFAULT
)
LOGGING
NOCOMPRESS
NOCACHE
NOPARALLEL
NOMONITORING;


DROP PUBLIC SYNONYM DUAL;

CREATE PUBLIC SYNONYM DUAL FOR SYS.DUAL;


GRANT SELECT ON SYS.DUAL TO APPS;

GRANT ALTER, DELETE, INDEX, INSERT, REFERENCES, SELECT, UPDATE, ON COMMIT REFRESH, QUERY REWRITE, DEBUG, FLASHBACK ON SYS.DUAL TO PUBLIC WITH GRANT OPTION;

GRANT SELECT ON SYS.DUAL TO SYSTEM WITH GRANT OPTION;