text: drop table if exists t1;
  
  create table t1 (f1 int, f2 int);
  insert into t1 values(1,1);
  insert into t1 values(2,null);
  insert into t1 values(2,null);
  insert into t1 values(2,3);
  insert into t1 values(2,2);
  select f1, f2 idx from t1 order by nvl(idx, 4);
  drop table t1;
  
  