Itemcode desc qty price coup_disc%  total
1.       ABC.  1.  100.            100
2.       Etc.  2.  150.            300
3.       Poj.  1.  50.   5

                                  G_total
                                   400
                                  Coup_disc
                                    20

My problem is this I want to calculate coupan disc
from g_total it's working but only when I go to
Same code suppose 3 if I moved to any other code like icode 2 or 3 etc so coup_disc is becoming null my code is 

Key-next-item

Coup_disc:=:g_tot/100*:coup_disc;

It should work if moved to any icode 

Sorry for bad English

Thanks

trigger key-next-item

block

control.A

DECLARE 
         l_match boolean:=false;
         l_continue boolean:=true;
         VV varchar2(30);
         aa number(8);
         bb varchar2(15);
         cc varchar2(8);
         dd varchar2(8);
         a number;
         b number;
         vn number;
         EE NUMBER;
ff number;
BEGIN 
    BEGIN 
  
        SELECT stk_code INTO :control.a FROM add_item
        WHERE add_item.stk_code=:control.a;
 
     EXCEPTION 
        WHEN NO_DATA_FOUND THEN 
        MESSAGE('Item code does not Excist');
        MESSAGE('Item code does not Excist');
        CLEAR_ITEM;
     RAISE FORM_TRIGGER_FAILURE;
     END;
		      go_block('itrn_bar');
	    	FIRST_rECORD;
	    	
	WHILE l_continue and not l_match LOOP
		select c_date 
 		       into 
             vv from add_item  where stk_code = :control.a;			
 	    if  to_char(sysdate,'mon-dd-yyyy hh:mi:ss')>=vv then
            message('!!! Coupan is Expired   '|| vv);
            message('!!! Coupan is Expired   '|| vv);
       go_block('control');
 	    end if;
 				IF :itrn_bar.item_Code=:CONTROL.a THEN 
	     	     :itrn_bar.qty:=:itrn_bar.qty+1;
             :itrn_bar.t_cost:=:itrn_bar.qty*:itrn_bar.unt_price;

		     	L_MATCH:=TRUE;
	ELSE
			if :system.last_record!='TRUE' THEN
				
	      NEXT_RECORD;
			ELSE
			L_CONTINUE:=FALSE;
	  
			END IF;
			END IF;
	
	END LOOP;
  
   next_RECORD;
   	 
IF NOT L_MATCH THEN
		   
   			select stk_code,description,qty,itm_dis,itm_tax,c_dis,unt_prc,ad_level2,op_typ,cust_no into 
   	     	   	:itrn_bar.item_Code,
   	     	   	:itrn_bar.item_name,
   	   	    	:itrn_bar.qty,
  	   	    :itrn_bar.dis_prc,
  	   	    :itrn_bar.tax,
   	   	    :itrn_bar.c_prc,
   	   	   
  	              aa,
        	    	bb,
    	   	    	cc,
 		        dd
   			  	        	from add_item,CLIENT
   			           where stk_code=:control.a and 
   			                CLIENT.cust_no=:imaster_bar.p_code;
				if cc='level2' then
          	:itrn_bar.unt_price:=bb;
		else
				    
  	:itrn_bar.unt_price:=aa;
		end if;
		
:itrn_bar.t_cost:=:itrn_bar.qty*:itrn_bar.unt_price;
:coupan_amt:=:ITRN_BAR.TCOST_TOTAL/100*:itrn_bar.c_prc;
	

END IF;
      
go_block('control');
go_item('control.a');
clear_block;
	
			END;

Item_code  desc.      Qty.  Unt_prc. C_disc  Total

1.         ABC.        1.    200.             200
C002.      10% disc.   1.     0.       10.    0 
2.         Device.     2.     150.            300
3.          Etc        1.     50.             50
                                       g_tot  230+50=270
                                       C_disc  3 should be 27

Sir this simple code
DECLARE 
         l_match boolean:=false;
        l_continue boolean:=true;
       VV DATE;
			BEGIN 
		      go_block('itrn_bar');
	    	FIRST_rECORD;
	WHILE l_continue and not l_match LOOP
		IF :itrn_bar.item_Code=:CONTROL.a THEN 
	     :itrn_bar.qty:=:itrn_bar.qty+1;
		     	L_MATCH:=TRUE;
	ELSE
			if :system.last_record!='TRUE' THEN
	      NEXT_RECORD;
			ELSE
  			L_CONTINUE:=FALSE;
			END IF;
			END IF;
	END LOOP;
   next_RECORD;
   	 
  
IF NOT L_MATCH THEN
	
		  --:EMP.cc =:CONTROL.zz then
   			select stk_code,description,qty,unt_prc,C_DIS into 
   	     	   	:itrn_bar.item_Code,
   	     	   	:itrn_bar.item_name,
   	   	    	:itrn_bar.qty,
   	   	    	:itrn_bar.unt_price,
   	   	      :itrn_bar.C_prc
        from add_item
               where stk_code=:control.a 
:itrn_bar.total:=:itrn_bar.qty*:itrn_bar.unt_price;
 END IF;
if :itrn_bar.item_code!=:control.a OR	L_MATCH=TRUE then
 	previous_record;
end if;
go_item('control.a');
clear_block;
END;

At coupan discount  field formula

:itrn_bar.G_tot/100*:itrn_bar.c_prc;