SQL & PL/SQL

hello all
My Table

create table mytb
( 
i_id   number,
q_num varchar2(20),
a_num  varchar2(20),
esp_dt date
)

insert into mytb values (1,'q1','a1',sysdate-20);
insert into mytb values (1,'q1','a2',sysdate-21);
insert into mytb values (1,'q1','a3',sysdate-22);
insert into mytb values (1,'q1','a4',sysdate-23);
insert into mytb values (1,'q2','a10',sysdate-20);
insert into mytb values (1,'q2','a12',sysdate-21);
insert into mytb values (1,'q2','a3',sysdate-22);
insert into mytb values (2,'q1','a1',trunc(sysdate));
insert into mytb values (2,'q1','a1',trunc(sysdate));

I am tring to get an output like

i_id  q_num  a_num 
1       q1         a1  
1        q2        a10
2        q1         a1

I need to group on i_Id and Q_num and need most recent A_num value for that
Any idea/suggestion will be helpful.

Thanks!

Edited by: user10647455 on Oct 7, 2011 1:38 PM

Edited by: user10647455 on Oct 7, 2011 1:39 PM

Edited by: user10647455 on Oct 7, 2011 1:39 PM

Edited by: user10647455 on Oct 20, 2011 7:04 AM