SQL>desc student
 Name                                      Null?    Type
 ----------------------------------------- -------- ---------------
 STUID                                     NOT NULL NUMBER(8)
 STATUS                                             VARCHAR2(30)
 CLASS                                              VARCHAR2(25)
 SECTION                                            VARCHAR2(30)
 NAME                                               VARCHAR2(250)
 F_NAME                                             VARCHAR2(250)
 DOA                                                DATE
 DOB                                                DATE

SQL> select count(stuid) from student
  2  where status='PRESENT'
  3  AND DOA <'26-DEC-2017';
COUNT(STUID)
------------
         1084

orclx>
orclx> conn sh/sh
Connected.
orclx> select sum(quantity_sold) from sales where trunc(time_id)='2001-12-31';

SUM(QUANTITY_SOLD)
------------------
               786

1 row selected.

orclx> select sum(quantity_sold) from sales where trunc(time_id)='31-DEC-2001';

SUM(QUANTITY_SOLD)
------------------


1 row selected.

orclx>

SQL> select count(stuid) from student;

COUNT(STUID)
------------
         1234

orclx>
orclx> host echo %nls_date_format%
yyyy-mm-dd:hh24:mi:ss

orclx> select sysdate from dual;

SYSDATE
-------------------
2018-04-09:15:44:19

1 row selected.

orclx> select to_Date('31-DEC-2001') from dual;

TO_DATE('31-DEC-200
-------------------
0031-12-20:01:00:00

1 row selected.

orclx>

SELECT distinct COUNT(STUDENT.STUID) str, 
STUDENT.CLASS||' '||STUDENT.SECTION sec, STUDENT.STUDENTID
FROM STUDENT
WHERE STATUS='PRESENT'
and doa < :p_1
GROUP BY STUDENT.CLASS||' '||STUDENT.SECTION, 
STUDENT.STUDENTID

CREATE TABLE STUDent ( 
stuid number(6) primary key,status varchar2(20),doa date,leav_date date);

insert into STUDent (stuid,status,doa,leav_date) 
values 
(1,'PRESENT','03-APR-2017','03-APR-2019');
insert into STUDent (stuid,status,doa,leav_date)
values 
(2,'N_PRESENT','23-APR-2017','03-MAY-2019');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(3,'PRESENT','03-APR-2017','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(4,'PRESENT','23-APR-2017','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(5,'PRESENT','13-APR-2017','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(6,'N_PRESENT','15-MAY-2017','03-APR-2019');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(7,'N_PRESENT','03-APR-2017','03-APR-2019');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(8,'N_PRESENT','23-MAR-2017','03-MAY-2019');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(9,'PRESENT','03-MAR-2016','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(10,'PRESENT','23-OCT-2018','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(11,'PRESENT','13-SEP-2017','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(12,'PRESENT','15-JUL-2018','');
insert into STUDent (stuid,status,doa,leav_date) 
values 
(13,'PRESENT','03-APR-2018','');

SQL> select to_date('03-APR-2017') from dual;
select to_date('03-APR-2017') from dual
               *
ERROR at line 1:
ORA-01858: a non-numeric character was found where a numeric was expected

SELECT distinct COUNT(STUDENT.STUID) str FROM STUDENT
WHERE STATUS='PRESENT'
and doa < :p_1

SQL> SELECT distinct COUNT(STUDENT.STUID) str,
  2  STUDENT.CLASS||' '||STUDENT.SECTION sec, STUDENT.STUDENTID
  3  FROM STUDENT
  4  WHERE STATUS='PRESENT'
  5  and doa < '08-FEB-2019'
  6  GROUP BY STUDENT.CLASS||' '||STUDENT.SECTION,
  7  STUDENT.STUDENTID;