Help req for check customer table maintenance with XD02 if not throw error

Question

hello ABAP GURUS,
check customer of the table maintenance with XD02 if not throw error i have given the codition for passing the values in the table but before that it has to check whether the customer i am passing in to the table is a customer from xd02.Here whatever no i am passing it is accepting it should not happen, but when i give the customer which is not a customer it should not accept but it has to throw the message as 'customer does not exist.Its urgent please help me
TYPES: BEGIN OF TY_KNVI,
KUNNR TYPE KUNNR,
TATYP TYPE TATYP,
TAXKD TYPE TAKLD,
END OF TY_KNVI.
DATA : VALIDFROM TYPE GUEBG,
VALIDTO TYPE GUEEN.
DATA : IT_KNVI TYPE STANDARD TABLE OF TY_KNVI,
WA_KNVI TYPE TY_KNVI OCCURS 0 WITH HEADER LINE.
DATA : V_NAME TYPE SYUNAME.
SELECT KUNNR
TATYP
TAXKD
FROM KNVI
INTO TABLE WA_KNVI
WHERE KUNNR = YYV_CFORM-KUNNR
AND TATYP = 'ZCST'
AND TAXKD = '1'.
V_NAME = SY-UNAME.
YYV_CFORM-ENTEREDBY = V_NAME.
IF SY-SUBRC NE 0.
MESSAGE E000(E4) WITH 'Please change the tax classification of ZCST as' '1' ', in Sales Area Data'.
ENDIF.
I have used the following code to enter the data into the table maintenance it is working fine and throwing the error when the tax type is not the one which i have given in the select statements but the problem is when i have given the customer no which is not there in the XD02 tcode, it is accepting and showing the error message as MESSAGE E000(E4) WITH 'Please change the tax classification of ZCST as' '1' ', in Sales Area Data'. now i have to check the customer no from XD02 and if it is existing in that tcode it should allow to save in the table maintenance otherwise throw a message as the 'Customer no does not exist, this I am unable to write so how can i check please help me .
thankx in advance.
Edited by: soni khadary on Apr 22, 2008 7:55 AM

Answer 1

Hi Kelly,
I guess <wa_tab>-handle_style is of type lvc_t_styl therefore you can do the following:
ls_edit-style = cl_gui_alv_grid=>mc_style_enabled.
"I assume you know your non-key fields' names so you can use subrotuine to perform update on each of them
ls_edit-fieldname =  'First field name' .
PERFORM update ls_edit.
ls_edit-fieldname =  'Second field name'.
PERFORM update ls_edit.
ls_edit-fieldname = 'Third field name'.
PERFORM update ls_edit
FORM update USING fs_edit type lvc_s_styl.
field-symbols: <style_tab> type lvc_t_styl,
                     <style_wa> type lvc_s_styl.
LOOP AT <tab> ASSIGNING <wa_tab>.
   if e_row = sy-tabix .
     "get you style table
     assign component 'HANDLE_STYLE' of structure <wa_tab> to <style_tab>.
     "as <style_tab> is typed fully you can read the row you are interested in
     read table <style_tab> assigning <style_wa> with key fieldname = fs_edit-fieldname
     if sy-subrc = 0.
       "update this entry
        <style_wa> = fs_edit.
*        modify table <style_tab> from <style_wa>. 
     endif.
   endif.
endloop.
endform.
Note!
Though, this should work, the use of RTTI as Uwe suggested would be best practise approach as far as dynamic programming is concerned. Anyhow it is still up to you which one you pick.
Regards
Marcin
I noticed now that this line is not necessary
modify table <style_tab> from <style_wa>. 
as we simply are working with field symbols, so changes made to <style_wa> are already visible in that table <style_tab>.
Edited by: Marcin Pciak on Mar 15, 2009 12:44 PM