adding random characters to $_GET variable

adding random characters to $_GET variable

I was just wondering if it was possible to add random characters to the
variable I am passing to the second page. I want this because if the user
changes the value in the url, then the system is gonna mess up because I
am inserting data to database based on the message id. I can't use session
because the first session is overriding the others.
If I have something like view_inbox.php?messageid=2 then the user can
change it to something view_inbox.php?message=4.
So is it possible to have some random characters like
view_inbox.php?messageid=GXLSsd2sdcds? The id is coming from database.
echo"<a
href='view_inbox.php?messageid=".$row['id']."'>".$row['from_user']."</a>";
view_inbox.php
$id = $_GET['messageid'];