ADD VALUES IN PL/SQL??

Question

My PL/SQL statement below doesn't return the desired outcome.
below variables A, B, & C are declared as VARCHAR2 data type.
D is declared as Number data type.
select (to_number(A)+to_number(B)+to_number(C) INTO D from dual;
I was expecting that D will have the sum of A, B, & C
However the Value of D is always 0.
Please help....

Answer 1

I am pasting the relevant portion of the script.
Code in BOLD RED is the issue. Expected PLSQL to return the sum of 3 variables though it is returning NULL.
<<CODE STARTS>>
DECLARE
    MY_FILE_DIR varchar2(40) := '/$ORACLE_TEMP';
    l_output        utl_file.file_type;
    v_file_handle varchar2(30) default 'Legacya.csv';
    buf varchar2(10230);
    v_ps_id varchar2(10);
    v_job_descr varchar2(40);
    v_comprate number;
    v_comprate_code varchar2(10);
    table_nm varchar2(50);
    max_date date;
    v_comp1 varchar2(10);
    v_comp2 varchar2(10);
    v_comp3 varchar2(10);
    v_comp4 varchar2(10);
    v_comp5 varchar2(10);
    v_comp6 varchar2(10);
    v_comp7 varchar2(10);
    v_comp8 varchar2(10);
    v_comp9 varchar2(10);
    v_comp_freq varchar2(10) default '';
    const1 varchar2(40) default 'A';
    const2 varchar2(40) default 'B'
    CURSOR C_EMP IS     
  SELECT
  EFFECTIVE_START_DATE
  , BELONGING_NAME
  , EMPLOYEE_NUMBER
  from apps.D
  where
  EFFECTIVE_START_DATE >= '2000/01/01'
  and EFFECTIVE_END_DATE <= '9999-12-31'
  and EMPLOYEE_NUMBER IN
  (select
                    EMP.EMPLOYEE_NUMBER AS EMPLOYEE_NUMBER
                from
                    apps.V EMP
                    , apps.D JOB
                where
                    EMP.EMPLOYEE_NUMBER = JOB.EMPLOYEE_NUMBER
                    and TO_CHAR( EMP.EFFECTIVE_END_DATE , 'YYYY-MM-DD')='9999-12-31' and EMP.USER_PERSON_TYPE='01-在籍者'
                    and TO_CHAR( JOB.EFFECTIVE_END_DATE , 'YYYY-MM-DD')='9999-12-31' order by EFFECTIVE_START_DATE DESC NULLS LAST
-- CURSOR ENDS
-- MAIN BODY BEGINS
BEGIN
FOR C_EMP_rec in C_EMP LOOP
  IF (C_EMP_rec.SG = 'C')  OR (C_EMP_rec.SG = 'S') THEN
select table_name,date_max INTO table_nm, max_date from
        select * from
        (select 'B' as table_name , Max (date_from) as date_max FROM Apps.B where EMPLOYEE_NUMBER=C_EMP_rec.EMPLOYEE_NUMBER UNION ALL select 'A' , Max (date_from) FROM APPS.A where EMPLOYEE_NUMBER=C_EMP_rec.EMPLOYEE_NUMBER UNION ALL
        select 'C' , Max (date_from) FROM Apps.C where EMPLOYEE_NUMBER=C_EMP_rec.EMPLOYEE_NUMBER) order by date_max DESC NULLS LAST)
        where rownum=1
-- assigning values to salary components
        IF table_nm = const1 THEN
        select comp1,comp2,comp3 INTO v_comp1,v_comp2,v_comp3 from APPS.A where    date_from=max_date and employee_number=C_EMP_rec.EMPLOYEE_NUMBER;
  v_comprate := to_number(v_comp1)+ to_number(v_comp2+ to_number(v_comp3);
    ELSIF
          <statements>
END;