Nhibernate querying oracle sequence

Use follwoing to get nextval of oracle sequence from hibernate

using (ISession session = //Get Nhibernate session)
{
var sqlQuery = session.CreateSQLQuery(query).AddScalar("NEXTVAL", NHibernateUtil.UInt64);


object result = sqlQuery.UniqueResult();

return Convert.ChangeType(result,typeof(long));

}