SQL & PL/SQL

Hi,

I am working on some retail related.our client is having some vendors.so every month we are calculating the total sales about the products.
Means we have "TotaL Current Sales" and Prevous "Month sales amt".
By using these two we are preparing statements for that particular vendor for that particular month and the previous month.
But the problem is am getting... when I am tryiyng to update the Previous MOnth amt it is getting updated but while preparing the statement it is showing the old value instead of new value.
can you please help me out to resolve it.

Eg : Current Month sales : 23,000,000
Previous MOnth Sales : 13,000,000

Here I have written the update statement to update the Previous month sales as 11,000,000.
then it is showing the sales as 11,000,000.
But while preparing the statement it is showing the Previous month sales as 13,000,000 only.But I want to display it as 11,000,000.

can you please help me out to write a query or Procedure/Function or any thing which is required for this.

Thanks in advance.