Clarification in flow

Question

Hi Experts....
My selection screen is as below
companycode---> mandatory
Channel id
origin id  ---> Mandatory
Bill date -
>  Mandatory
my channel id is in a z table and stored in the table like
5801
5802
5803
in order to link this in the next table (xblnr-Bkpf) the channel id is stored as
5801-3605T
5801-3605R
5801-3605s
I need to cut the remaining half from - "hyphen' and link with the bkpf table
(i.e) 5801 from z table and all that satisfies with 5801 in xblnr-BKPF
My doubts is that....
1. is it neccessary to check channel id for is not inital ,  since it is notobligatory in my selection screen.
2. is it right to concatenate and check for  '-' hyphen  or i should
split and check .....
If iam wrong in the coding, can you please correct me?????
Thankx in advance
Rachel
part of my coding
===============
select channel_id from zft_oa_channel into corresponding fields of table it_zchannel
                                                where channel_id = pr_chaid.
if it_zchannel[] is not initial.
concatenate pr_chaid+0(4) '%' into pr_chaid.
select bukrs belnr gjahr bldat xblnr from bkpf into corresponding fields of table it_bkpf
                                              where bukrs = pr_bukrs
                                              and    bldat in so_bldat
                                              and    blart = 'AR'
*and    belnr = wa_bkpf-belnr
*and    gjahr = wa_bkpf-gjahr
                                              and    xblnr like pr_chaid.
endif.
if it_bkpf[] is not initial.
select bukrs belnr gjahr  xref1 xref2 kunnr dmbtr  from bseg into corresponding fields of table it_bseg
                                          for all entries in it_bkpf
                                           where  bukrs = it_bkpf-bukrs
                                                  and belnr = it_bkpf-belnr
                                                  and gjahr = it_bkpf-gjahr.
                                                 and kunnr =  wa_bseg-kunnr.
endif.
if it_bseg[] is not initial.
select  kunnr  name1 locco  from kna1 into corresponding fields of table it_kna1
                                      for all entries in it_bseg
                                        where  kunnr = it_bseg-kunnr and
                                                locco = pr_locco.
endif.
loop at it_bseg into wa_bseg where belnr = wa_bseg-belnr.    
   wa_final-kunnr = wa_bseg-kunnr.
   wa_final-xref1 = wa_bseg-xref1.
   wa_final-xref2 = wa_bseg-xref2.
   wa_final-dmbtr = wa_bseg-dmbtr.
   read table it_bkpf into wa_bkpf  with key belnr = wa_bkpf-belnr.       
if sy-subrc = 0.
    wa_final-xblnr = wa_bkpf-xblnr.
    wa_final-bldat = wa_bkpf-bldat.
  endif.

Answer 1

1. If Channel ID can be BLANK and still you are looking for the output then no need to check for NULL.
but, if has to get some value then its betterto check for NULL to avoid unnecessary processing.
2. You can do as you want to, SPLIT or CONCATENATE.