Managing Credit,Debit and Balance is become my headache.

Question

Managing  Credit,Debit and Balance is become my headache ..if any one has solution for that please give me solution as fast as possible.

Description ::

I have to manage account of Retailers for that I have a table named RetailerAccount. 

Table is like as shown below :

Note : All the date are dd-MM-yyyy formate

Opening Balance :1000

ID Date Credit Debit Balance

1 1/12/2010 500 500

2 1/12/2010 200 700

3 2/12/2010 100 600

4 3/12/2010 300 300

5 4/12/2010 100 400

1) Problem 

Now, Problem is that if Credit is changed or deleted of 1/12/2010 then Balance will effected till the 4/12/2010. 

Here is the only shown 5 data but when  it is increase in large amount of data and if any chang done in credit and debit in half of them then how to 

change balance till the last record?

2) Problem 

Suppose today is 4/12/2010 and I am adding credit or debit for the 1/12/2010 then how to manage it?

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I am making  project and this is the 2 major problem for me. 

If you  have any alternate solution then give me it also.

I am very oblige if you solved out my problem.