Accept prompt 'Number of days of report:' 
DECLARE 
    i         NUMBER; 
    dt        VARCHAR2(1000); 
    cnt       VARCHAR2(1000); 
    x         VARCHAR2(1000); 
    start_day NUMBER; 
    end_day   NUMBER; 
BEGIN 
    i := &1; 

    SELECT To_char(Trunc(SYSDATE - i), 'RRRRMMDD') 
    INTO   start_day 
    FROM   dual; 

    SELECT To_char(Trunc(SYSDATE), 'RRRRMMDD') 
    INTO   end_day 
    FROM   dual; 

    IF ( i < 10 ) THEN 
      FOR a IN (SELECT partition_name 
                FROM   user_tab_partitions 
                WHERE  table_name = 'PART_TEST_DETAILS' 
                       AND Substr(partition_name, 10) >= start_day 
                       AND Substr(partition_name, 10) < end_day) LOOP 
          BEGIN 
              x := 
      'select TRUNC(process_date),COUNT(*) from PART_TEST_DETAILS partition(' 
      ||a.partition_name 
      ||')  where status in (''J'',''K'',''S'') group by trunc(process_date)' 
              ; 

              dbms_output.Put_line(x); 

              EXECUTE IMMEDIATE x INTO dt, 
                                       cnt; 

              dbms_output.Put_line(dt 
                                   ||' ' 
                                   ||cnt); 
          EXCEPTION 
              WHEN OTHERS THEN 
                NULL; 

                dbms_output.Put_line('No Records for this partition'); 
          END; 
      END LOOP; 
    ELSE 
      dbms_output.Put_line ('Number of days is greater than 10'); 
    END IF; 
END; 

/ 

select trunc(process_date), count(*) from mytable group by trunc(process_date);

SQL> select TRUNC(process_date),COUNT(*) from PART_TEST_DETAILS partition(PART_TEST_20140220) where status in ('J','K','S') group by trunc(process_date);

TRUNC(PRO   COUNT(*)
--------- ----------
20-FEB-14    4772220
21-FEB-14      21097

Enter value for 1: 1
old   9: i :=&1;
new   9: i :=1;
select TRUNC(process_date),COUNT(*) from PART_TEST_DETAILS partition(PART_TEST_20140220) where status in ('J','K','S') group by trunc(process_date);
No Records for this partition