Hi Guys,

Anyone here knows how to create a query that will produce something like the tables below.

I have an Item A that costs 10 but in a few days the Item A was changed to 15. I need to know how much I need to add as an additional fee or if there's a need for reimbursement.

Code:
[U]Date[U]    TypeOfWork    UnitPrice  AccountsPayable
1/10/2009     Item A                     10                     10
1/11/2009     Item A                     15                     5
But what if the same Item was changed again for the third time.


Code:
[U]Date[U]    TypeOfWork    UnitPrice  AccountsPayable
1/10/2008     Item A                     10                    10
1/11/2008     Item A                     15                    5
1/20/2008     Item A                     13                    -2
I need to show everything in the query to determine how many times Item A changed in price. Negative values under AccountsPayable are the amounts subjected for reimbursement and the positive values are those I need to pay as an additional fee.

If I am going to code it in excel the formula is something like this;

Code:
[Col4, Row1] =[Col3,Row1]
[Col4, Row2] =[Col3,Row2]-[Col3,Row1]
[Col4, Row3] =[Col3,Row3]-[Col3,Row2]