How to find sum

[RoniDxb]

AccountNo.....Date........Amount
1..................1/25/2008...500
1..................1/26/2008...500
1..................1/27/2008...500
1..................1/27/2008...500
1..................1/28/2008...500

I have a table named Table1 that has following structure.
I take three parameters from users as Starting Date , Ending Date and Account No
for example if user give the follwing parameters
Account No = 1
Starting Date = 1/27/2008
Ending Date = 1/28/2008

result of Report
AccountNo.....Date........Amount
1..................1/27/2008...500
1..................1/27/2008...500
1..................1/28/2008...500


Total Amount = 1500

Now the problem is i want to show the last previous Sum of this account too
for example in this case previous Balance will be

Previous Balance = 1000

plz guide me how can i take out prevous balance in Ctystal Report

[VBFnewcomer]

Now the problem is i want to show the last previous Sum of this account too
for example in this case previous Balance will be

Previous Balance = 1000

what do you mean by previous balance and how would anybody know what was the prev transaction (unless you are holding the same in another table or something)
pls elaborate...

[jggtz]

Try inserting a numeric formula

WhileReadingRecords;
numberVar Balance := Balance + {Table1.Amount};