Okay, I've never worked with Oracle (and my ODBC memory is foggy), but I'm going to take a few blind stabs in the dark here and I hope it'll be enough to get you started in the right direction.

First off,

use strict;
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it's a really good habit to get into. For instance, in your script, what is $Sql_test?
Also, in the line:

$db = new Win32::ODBC("DSN=clamon.world;UID=scott;PWD=tiger");
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The documentation I have suggests that you can connect with only the DSN name. (this is the part where the cross the "t's and dot the i's" comes in, but) Make sure that you have the proper driver installed for your DSN type, and try embedding the username and password in the DSN (most of the drivers I've seen will allow you to actually do that).

If in doubt, you could also use ADO (assuming you are on a windows 2000 or higher machine).

use strict;
use Win32::OLE;
my $db = CreateObject OLE "ADODB.Connection";
$db or die "Whoa partner!";
$db->Open("DSN=clamon.world;UID=scott;PWD=tiger");
my $rs = $db->Execute("SELECT * FROM EMP where EMPNO = 7900");
print ($_)->{Description}."<br>\n" foreach(keys %{$db->Errors()}) unle
+ss($rs);

while(!$rs->EOF){
  #see the ADO documention for getting out the data you want 
  $rs->MoveNext();
}
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This is of course an alternate suggestion to try if you're banging your head against this horribly. Note, I haven't tested this, so treat it as if you would any psuedocode. Good luck with it.
    --jay