How to add leading zero in a number in Oracle with to_number function - sql

Question

create or replace FUNCTION OT_TIMMING_CHECK
(V_OT_ROOM_ID NUMBER,V_OPERATION_DATE DATE,V_START_TIME VARCHAR2,
V_END_TIME VARCHAR2)
RETURN NUMBER AS
V_STATUS_1 VARCHAR2(10);
V_STATUS_2 VARCHAR2(10);
V_STATUS_3 VARCHAR2(10);
V_STATUS_4 VARCHAR2(10);
V_STATUS_5 VARCHAR2(10);
V_STATUS_6 VARCHAR2(10);
C_END_TIME NUMBER;
C_START_TIME NUMBER;
F_OPERATION_DATE DATE;
V_COUNT NUMBER :=0;
b_start_time varchar(10);
BEGIN
SELECT OPERATION_DATE INTO F_OPERATION_DATE FROM OT_THEATRE_STATUS_TBL1
WHERE OPERATION_DATE = V_OPERATION_DATE AND ROWNUM<2 ;
SELECT (case when (substr(V_START_TIME,1,instr(V_START_TIME,':')-1))='00'
then 24
else to_number(substr(V_START_TIME,1,instr(V_START_TIME,':')-1)) end) INTO
C_START_TIME from dual;
SELECT (case when (substr(V_END_TIME,1,instr(V_END_TIME,':')-1))='00' then
24 else to_number(substr(V_END_TIME,1,instr(V_END_TIME,':')-1)) end) INTO
C_END_TIME from dual;
IF V_OT_ROOM_ID=1 AND F_OPERATION_DATE = V_OPERATION_DATE THEN
WHILE (C_START_TIME < C_END_TIME)
LOOP
SELECT STATUS_1 INTO V_STATUS_1 FROM OT_THEATRE_STATUS_TBL1
WHERE START_TIME=concat(to_char(C_START_TIME),':00:00')
AND END_TIME= REPLACE(concat(to_char(C_START_TIME+1),':00:00'),24,'00');
IF(V_STATUS_1 ='Booked' OR V_STATUS_1='Pending') then
RETURN 1;
ELSE
C_START_TIME:= TO_CHAR(C_START_TIME+1);
V_COUNT:=V_COUNT+1;
end if;
END LOOP;
RETURN 0;
END IF ;
END;
Database structure is like this
V_START_TIME V_END_TIME OPERATION_Date STATUS_1 OT_ROOM_ID_1
01:00:00 01:00:00 24-Mar-17 AVAILABLE 1
02:00:00 02:00:00 24-Mar-17 LAPSED 1
03:00:00 03:00:00 24-Mar-17 AVAILABLE 1
04:00:00 04:00:00 24-Mar-17 AVAILABLE 1
05:00:00 05:00:00 24-Mar-17 AVAILABLE 1
06:00:00 06:00:00 24-Mar-17 AVAILABLE 1
07:00:00 07:00:00 24-Mar-17 AVAILABLE 1
08:00:00 08:00:00 24-Mar-17 AVAILABLE 1
09:00:00 09:00:00 24-Mar-17 AVAILABLE 1
10:00:00 10:00:00 24-Mar-17 AVAILABLE 1
11:00:00 11:00:00 24-Mar-17 AVAILABLE 1
12:00:00 12:00:00 24-Mar-17 AVAILABLE 1
13:00:00 13:00:00 24-Mar-17 BOOKING 1
14:00:00 14:00:00 24-Mar-17 AVAILABLE 1
15:00:00 15:00:00 24-Mar-17 AVAILABLE 1
16:00:00 16:00:00 24-Mar-17 AVAILABLE 1
17:00:00 17:00:00 24-Mar-17 AVAILABLE 1
18:00:00 18:00:00 24-Mar-17 AVAILABLE 1
19:00:00 19:00:00 24-Mar-17 AVAILABLE 1
20:00:00 20:00:00 24-Mar-17 AVAILABLE 1
21:00:00 21:00:00 24-Mar-17 AVAILABLE 1
22:00:00 22:00:00 24-Mar-17 AVAILABLE 1
23:00:00 23:00:00 24-Mar-17 AVAILABLE 1
00:00:00 00:00:00 24-Mar-17 AVAILABLE 1
Earlier V_START_TIME like '1:00:00:00' but now it is leading with 0. Then problem comes. Now it is returning null. How to come out from this problem.

Answer 1

Number won't be having leading zero's
Can you try the following:
LPAD(to_number(SUBSTR('01:00:00',1,instr('01:00:00',':')-1)),2, 0)
reference:
How to display the leading zero's in a number of oracle

Answer 2

yes, try it
SELECT (
CASE
WHEN (SUBSTR('01:00:00',1,instr('01:00:00',':')-1))='00'
THEN '24'
ELSE LPAD(SUBSTR('01:00:00',1,instr('01:00:00',':')-1),2,'0')
END)
FROM dual;