Calculating field based on value of another field in previous record

[accessbro]

I'm trying to create something like an online banking view that shows the running balance as each transaction occurs. I have tblTransactions with fields AccountNumber, ItemDescription, and TransactionAmount. I'm trying to create something that shows these three fields and a fourth field with the running balance. So if I initially deposit $100 it will show the first record with TransactionAmount = $100 and RunningBalance = $100. Then the next transaction will subtract the Transactionamount for the new record from the RunningBalance from the previous record to get the RunningBalance for the new record. So if I make a purchase for $2, the AvailableBalance for that record is $98. Is this possible with a query? Here's a picture to describe what I'm talking about:

[June7]

Not easy in query or form. Review http://allenbrowne.com/subquery-01.html#AnotherRecord

Textbox on report has a RunningSum property that might serve.

[qa12dx]

use the dsum function.

simple eg.

table1
id - autonum
amt - num
tran - num (1 or -1 debit/credit)

create a query, the runing sum col will be;
run_sum: DSum("amt*tran","Table1","id<=" & [id])

read the criteria part carefully.


since my data is in order of entry, i'm using the id field.



and the result

[accessbro]

use the dsum function.

simple eg.

table1
id - autonum
amt - num
tran - num (1 or -1 debit/credit)

create a query, the runing sum col will be;
run_sum: DSum("amt*tran","Table1","id<=" & [id])

read the criteria part carefully.


since my data is in order of entry, i'm using the id field.



and the result

I haven't tried it yet but this looks like exactly what I need. Thank you very much sir.