Why is there a data type NUMC?

Question

Hi ABAP masters,
working in database support for several years I've very often seen the problems that arise from the awkward data type NUMC.
A numeric type stored as characters.
What I always wondered is: what is this data type really good for?
The leading zero output display alone is hardly a valid reason to waste storage and complicate the usage of the data of that type.
I cannot imagine any use for this data type that wouldn't be better done by using integer types.
So, if you know what the reasoning behind this data type is, please let me know.
thanks and best regards,
Lars

Answer 1

NUMC data type can be used to maintain positive numbers with leading Zeros
Most of SAP's important numbers like Sales Order numbers, Customer numbers, Delivery documents,
Material numbers, Sales Org, Division, Company Codes, Distribution Channel are CHARs only
But if their Data is containing only digits, SAP Transactions will automatically add Leading zeros for them and store in the database as Raw data.
If those SAP numbers contains at least one non-digit character, then leading zeros will not be added.
Example: if 54 is assigned to BUKRS it will be stored in DB as 0054
               if 5A is assigned to BUKRS it will be stored in DB as 5A only
Leading zero concept is very useful for Date and Time calculations.
Month, Day, hours etc., must be declared as NUMC for better calculations
Example:
    PARAMETERS p_year TYPE I.          "instead of Integer we can use type N LENGTH 4 also here
    DATA  v_month TYPE N LENGTH 2.
    DATA  v_day     TYPE N LENGTH 2.
    DATA  v_year    TYPE N LENGTH 4.       then calculations will be easy
    DATA  FDATE   TYPE D.
    v_year = p_year.
    v_day  = 1.              "1st day of Month
    DO 12 TIMES.
        v_month = sy-index.           "Leading zero will be added automatically
        CONCATENATE v_year  v_month  v_day  INTO  FDATE.
        WRITE / FDATE.                "Every month 1st day of selected year
    ENDDO. 
Example:  Customer number contains uneven digits.  It should be converted to a 10 digit number
                 with "C" as 1st Character.  Logic will be
                 PARAMETERS custno TYPE I.               
                 DATA  v1                     TYPE  N  LENGTH  10.
                 DATA  str_custno         TYPE C LENGTH 11.
                 v1 = custno.       "customer number will be converted to 10 digit number
                 CONCATENATE 'C'  V1   INTO  str_custno.
please correct me, if I am wrong
Thanks and Regards
Nagababu Tubati