Table Column Sum using LINQ with Where Clause

var res = (from x in dbcon.tbl_R_Bill
                where x.PartsSalesOrderSL == id
                select x.PaidAmount).Sum();

txtTotalPaidAmount.Text = res.ToString();

Conditional count in Crystal Report XI

My Table Structure is this.

Now we will count how many student are passed & failed in the report footer. Look Like This

For This Output We need to use a Running Total Field.

Create a running total
>> Field to summarize : Result.Use Count for field.
Under Evaluate section: select "Use a formula".
Click on the icon next to this and write {result}='pass'.
Then it will only calculate the number of students Passed.
The same way applies to find the count of Failed students.