create table t2(
      root_id number,
      id number,
      name varchar(5),
      description varchar(10)
      );
    insert into t2(root_id,id,name,description) values(0,1,'a','aaa');
    insert into t2(root_id,id,name,description) values(1,2,'a1','aaa1');
    insert into t2(root_id,id,name,description) values(1,3,'a2','aaa2');
    insert into t2(root_id,id,name,description) values(0,4,'b','bbb');
    insert into t2(root_id,id,name,description) values(4,5,'b1','bbb1');
    insert into t2(root_id,id,name,description) values(4,6,'b2','bbb2');
    insert into t2(root_id,id,name,description) values(6,7,'7b2','bbb2');
    insert into t2(root_id,id,name,description) values(-1,-2,'-a','-aaa');
     insert into t2(root_id,id,name,description) values(-2,-5,'-a','-aaa');
    create table t3(id number);
    insert into t3(id)values(7);
    insert into t3(id)values(3);insert into t3(id)values(6);
    select * from t2
    select substr(sys_connect_by_path(id,':'),2,2),connect_by_isleaf,T2.* from  t2 
    where connect_by_isleaf = 1 
    start with id  in (select id from t2)
    connect by prior root_id = id