UPDATING Table Column with new Entry

I am working on Oracle APEX. I want my report to show me the updated Debit value in Total amount column.The Report Query is shown in the following diagram mentioned below.

TABLE  "VENDOR_ACCOUNT" 
(  "VEN_ACCOUNTID"      NVARCHAR2(10), 
   "VEN_REGNO"          NVARCHAR2(10), 
   "VEN_TXDATE"         DATE, 
   "VEN_INVOICE_REFNO"  NVARCHAR2(10), 
   "TOTALAMOUNT"        NVARCHAR2(10), 
   "IN"                 NUMBER(10,0), 
   "OUT"                NUMBER(10,0) 
) 

SELECT "VEN_ACCOUNTID" , 
       "VEN_REGNO" , 
       "VEN_TXDATE" , 
       "VEN_INVOICE_REFNO" , 
       "TOTALAMOUNT" , 
       "IN",
       "OUT",   
       "TOTALAMOUNT"+"IN" as "CREDIT",
       "TOTALAMOUNT"-"OUT" as "DEBIT"
FROM Vendor_Account;

Required Scenario: I want to update the TotalAmount Column with Debit and Credit. The new Debit or Credit value has to be shown in the TotalBalance column on the next record.

Answer

You can use Oracle analyitic function LAG:

Select "VEN_ACCOUNTID" , 
        "VEN_REGNO" , 
        "VEN_TXDATE" , 
        "VEN_INVOICE_REFNO" , 
        "TOTALAMOUNT" , 
        "TOTALAMOUNT" + lag("IN",1) over (ORDER BY "VEN_ACCOUNTID")
                      - lag("OUT",1) over (ORDER BY "VEN_ACCOUNTID") AS "NEW_TOTALAMOUNT",
        "IN",
        "OUT",  
        "TOTALAMOUNT"+"IN" as "CREDIT",
        "TOTALAMOUNT"-"OUT" as "DEBIT"
FROM    Vendor_Account;