By using order by clause,i'm not getting correct order. I need month wise dates : select (TO_CHAR(TRUNC(exec_end),'DD-MON-YY'))    
 from tbl_dumps
where exec_end >=to_date(sysdate-90) group by TO_CHAR(TRUNC(exec_end),'DD-MON-YY'),
TO_CHAR(TRUNC(exec_end),'MON') order by (TO_CHAR(TRUNC(exec_end),'MON')) desc)