java.sql.SQLException: ORA-03115: unsupported network datatype or representation
This error appears when you try to get a field by name ( rs.getString("uname") in your case) which is not in the resultset.
And like igr said, you are trying to get the email field ( with rs.getString("email") ) and it's not in the query, so this is your error.
I found this conversation because I was getting the same error in an application when I was trying to get a field with an whitespace at the end of the string ( rs.getString("uname ") instead of rs.getString("uname" ).
And I just fix it using the correct name for the field I was getting from the query.
I hope it is useful! ;)