SQL> select user_name,to_char(dt, 'dd.mm.yyyy hh:mi')  from Oracledb.Logoff where user_name='user';

USER_NAME
--------------------------------------------------------------------------------
TO_CHAR(DT
----------------
user
 11 . 11 . 2005   05 : 06 

user
 27 . 02 . 2006   11 : 35 

user
 28 . 02 . 2006   11 : 07 

$stmt = ociparse($conn,"select USER_NAME,to_char(dt, 'dd.mm.yyyy hh:mi') from Oracledb.Logoff where USER_NAME='".$user."'");
ociexecute($stmt,OCI_DEFAULT);
echo "<table>\n";
$i= 1 ;
  while (ocifetch($stmt)){
    echo "<tr><td>".$i.
        "</td><td>".ociresult($stmt,"USER_NAME").
        "</td><td>".ociresult($stmt,"DT").
        "</td></tr>\n";
    $i++;
}
echo "</table>";
echo "<b>Всего строк: </b>".OCIRowCount($stmt);

результат в браузере вижу такой
1	user	11-NOV-05
2	user	27-FEB-06
 Всего строк:  12

$stmt = ociparse($conn,"select USER_NAME, DT from Oracledb.Logoff where USER_NAME='".$user."'");

$stmt = ociparse($conn,"select USER_NAME,to_char(DT, 'dd.mm.yyyy hh:mi') from Oracledb.Logoff where USER_NAME='".$user."'");

"</td><td>".ociresult($stmt,"DT").

"</td><td>".ociresult($stmt, 2 ).

1	user	11.11.2005 05:06
2	user	27.02.2006 11:35