How to get a running balance on a report

Question

How do I get a running balance for one customer. Please look at the data set as a example and advise. 
Customer A  Apples
1.00 Paid
Customer A Pears
2.00 Paid
Customer A Oranges
2.50 Open
Balance  2.50
What expression am I to use in report builder 
Thanks

Answer 1

Hi,
Here is the example for getting running Value:
http://gerryhubi.wordpress.com/2010/03/16/ssrs-tips-runningvalue/
SSRS Tips – RunningValue
Posted on March
16, 2010by gerryhu2000
Running value is a very generic and useful function.  All
the 3 parameters can be manipulated for different purpose.
·         Expression
the target on which the aggregation is applied. Most of the time it’s the column name in a dataset, or a combination of a few columns, e.g. “Group1 & Group2”.
·         Function
Aggregate functions, and the most often used functions include
Avg
Returns the average of all non-null numeric values specified by the expression
Count
Returns a count of non-null values specified by the expression
CountDistinct
Returns a count of all distinct non-null values specified by the expression
Max
Returns the maximum value of all non-null numeric values specified by the expression.
You can use this for specifying a chart axis maximum value to control the scale.
Min
Returns the minimum value of all non-null numeric values specified by the expression.
You can use this for specifying a chart axis minimum value to control the scale.
Sum
Returns the sum of all the non-null numeric values specified by the expression
·         Scope
The scope can be dataset, table or table groups.
The sample report below shows some applications of RunningValue. The dataset uses this query
SELECT Company, Product, InvoiceNumber, InvoiceAmount from InvoiceTable
The table (SSRS table control) is configured to have 2 groups, “gCompany” and “gProduct”.
Here is a report featured with Running Value tips
Alternate
color for Product Group
Normally the “green-bar” (green background color for alternate rows) is implemented by setting
the back ground color of the detail row to
  =IIF(RowNumber(Nothing)
Mod 2,"Green","White")
To set color for alternate groups, use the expression below for background color
=IIF(RunningValue(Fields!Product.Value,CountDistinct,Nothing)
Mod 2, "LightBlue", "White")
The RunningValue function works like a counter/index for the product group.
Running
Sum value
Cumulative sum is calculated in this expression:
=RunningValue(Fields!Amount.Value,
SUM, Nothing)
“Scope = Nothing” means the outermost data region. And for Running Sum by Company or Product,
the scope if set to the corresponding group name.
=RunningValue(Fields!Amount.Value,
SUM, “gCompany”) or
=RunningValue(Fields!Amount.Value,
SUM, “gProduct”)
Group
Running Number
The summary table uses the same dataset as the details table. Normally the row number uses the
function
= RowNumber(“table1”)
For this case, the row number is using the CountDistinct function. The expression is
=RunningValue ( Fields!Company.Value +
Fields!Product.Value,
CountDistinct, Nothing)
Notice that the 2 groups are both used, to prevent mixing products
from different company.
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