Tom, I have not tested this statement, but I think it would produce the desired results.

SELECT a.empno
,a.ename
,a.sal
,b.empno
,b.ename
,b.sal
,c.empno
,c.ename
,c.sal
FROM (SELECT rownum rn, empno, ename, sal
FROM emp
ORDER by empno) a
,(SELECT rownum rn, empno, ename, sal
FROM emp
ORDER by empno) b
,(SELECT rownum rn, empno, ename, sal
FROM emp
ORDER by empno) c
WHERE MOD(a.rn,3) = 1
AND MOD(b.rn,3) = 2
AND MOD(c.rn,3) = 0
AND a.rn = b.rn + 1
AND a.rn = c.rn + 2
ORDER by a.empno;

Hi Tom, please,
reading </code> http://www.odtug.com/2000papers/cassidy.pdf

I found how to create a ddl trigger 

1)I was searching about more information in DBMS_STANDARD standard package and I can't found, I can't believe that.
Do you know where is a detailed explanation of that package (ora9ir2)
DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type

I searched

http://www.google.com/search?q=DBMS_STANDARD.DICTIONARY_OBJ_NAME&ie=UTF-8&oe=UTF-8&hl=es&lr= <code>
and it seems this is the only one paper around the world that uses this

2) How can I get the session is to link in the database trigger
CREATE OR REPLACE TRIGGER SYS.TGR_CREATE
AFTER
CREATE
ON DATABASE
BEGIN
END;
to the session to get the machine name, os user, etc.
3) Why when I create an alter trigger and a create trigger only one of them works, I suppose is a bug, or this always work in that way and there is a trick.
I tried several times
creating object
altering object
dropping object

And I can't get alter and create works at the same time.
CREATE OR REPLACE TRIGGER sys.tgr_drop
AFTER
DROP
ON DATABASE
BEGIN
INSERT INTO SYS.ddls
(dd2_user, dd2_time, dd2_objeto, dd2_tipo)
VALUES(
'D-'||DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type
);
END;
/
CREATE OR REPLACE TRIGGER sys.tgr_create
AFTER
CREATE
ON DATABASE
BEGIN
INSERT INTO SYS.ddls
(dd2_user, dd2_time, dd2_objeto, dd2_tipo)
VALUES(
'C-'||DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type
);
END;
/
CREATE OR REPLACE TRIGGER sys.tgr_alter
AFTER
alter
ON DATABASE
BEGIN
INSERT INTO SYS.ddls
(dd2_user, dd2_time, dd2_objeto, dd2_tipo)
VALUES(
'A-'||DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type
);
END;
/

Thanks Tom

I did them in this way, any comment (except the use of sys account I'm using only to test in test database)
Now I changed the trigger, I couldn't reproduce the problem with alter and create trigger, now is working fine, if there was some problem now is fixed :).

CREATE OR REPLACE TRIGGER sys.tgr_ALTER
AFTER
ALTER
ON DATABASE
DECLARE
csql_text ora_name_list_t;
n NUMBER;
cSQL CLOB;
var_user varchar2(30);
var_osuser varchar2(30);
var_machine varchar2(64);
var_process varchar2(09);
var_program varchar2(48);
var_sqltext varchar2(1000);
BEGIN
select s.username, s.osuser, s.machine, s.program
into var_user, var_osuser, var_machine, var_program
from sys.v_$session s
,sys.v_$sqlarea t
where s.audsid = userenv('sessionid')
and s.prev_sql_addr = t.address(+)
and s.prev_hash_value = t.hash_value(+)
and username is not null;

n:= ora_sql_txt(csql_text);
FOR I IN 1..N LOOP
cSQL:=cSQL||csql_text(i);
END LOOP;



INSERT INTO SYS.ddls
(dd2_user, dd2_time, dd2_objeto, dd2_tipo,DD2_SQL,
DD2_OSUSER , DD2_MACHINE , DD2_OPROGRAM
)
VALUES(
'A-'||DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type,cSQL,
var_osuser, var_machine, var_program
);
END;
/

CREATE OR REPLACE TRIGGER sys.tgr_create
AFTER
CREATE
ON DATABASE
DECLARE
csql_text ora_name_list_t;
n NUMBER;
cSQL CLOB;
var_user varchar2(30);
var_osuser varchar2(30);
var_machine varchar2(64);
var_process varchar2(09);
var_program varchar2(48);
var_sqltext varchar2(1000);
BEGIN
select s.username, s.osuser, s.machine, s.program
into var_user, var_osuser, var_machine, var_program
from sys.v_$session s
,sys.v_$sqlarea t
where s.audsid = userenv('sessionid')
and s.prev_sql_addr = t.address(+)
and s.prev_hash_value = t.hash_value(+)
and username is not null;

n:= ora_sql_txt(csql_text);
FOR I IN 1..N LOOP
cSQL:=cSQL||csql_text(i);
END LOOP;



INSERT INTO SYS.ddls
(dd2_user, dd2_time, dd2_objeto, dd2_tipo,DD2_SQL,
DD2_OSUSER , DD2_MACHINE , DD2_OPROGRAM
)
VALUES(
'C-'||DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type,cSQL,
var_osuser, var_machine, var_program
);
END;
/

CREATE OR REPLACE TRIGGER sys.tgr_drop
AFTER
DROP
ON DATABASE
DECLARE
csql_text ora_name_list_t;
n NUMBER;
cSQL CLOB;
var_user varchar2(30);
var_osuser varchar2(30);
var_machine varchar2(64);
var_process varchar2(09);
var_program varchar2(48);
var_sqltext varchar2(1000);
BEGIN
select s.username, s.osuser, s.machine, s.program
into var_user, var_osuser, var_machine, var_program
from sys.v_$session s
,sys.v_$sqlarea t
where s.audsid = userenv('sessionid')
and s.prev_sql_addr = t.address(+)
and s.prev_hash_value = t.hash_value(+)
and username is not null;

n:= ora_sql_txt(csql_text);
FOR I IN 1..N LOOP
cSQL:=cSQL||csql_text(i);
END LOOP;



INSERT INTO SYS.ddls
(dd2_user, dd2_time, dd2_objeto, dd2_tipo,DD2_SQL,
DD2_OSUSER , DD2_MACHINE , DD2_OPROGRAM
)
VALUES(
'D-'||DBMS_STANDARD.LOGIN_USER,SYSDATE,
DBMS_STANDARD.DICTIONARY_OBJ_NAME,
DBMS_STANDARD.dictionary_obj_type,cSQL,
var_osuser, var_machine, var_program
);
END;
/

Thanks Tom, could you fix one trigger please,if I'm not abusing from you. please

Hi Tom,
You have said,
<quote>
stop using dbms_standard
start using the documented functions.
<quote>

What is the difference?
Why should not we use?
Is there any specific reason to use?

Really Thanks Tom