Database

private void Form1_Load(object sender, EventArgs e)
{
    reportViewer1.ServerReport.ReportServerUrl = new Uri("http://192.168.2.5/reportserver");
    reportViewer1.ServerReport.ReportServerCredentials.NetworkCredentials = CredentialCache.DefaultCredentials;

    string reportFile = @"C:\Report Project1\Report1.rdl";
    reportViewer1.ServerReport.ReportPath = reportFile;
    reportViewer1.ProcessingMode = ProcessingMode.Remote;

    reportViewer1.ServerReport.DisplayName = "Corporate View Report";

    ReportParameter[] parameters = new ReportParameter[3];
    parameters[0] = new ReportParameter("@ProjectId", "6");
    parameters[1] = new ReportParameter("@PrimaryWhseId", "8293");
    parameters[2] = new ReportParameter("@SecondaryWhseId", "8290");
    reportViewer1.ServerReport.SetParameters(parameters);

    try
    {
        reportViewer1.RefreshReport();
    }
    catch(Exception ex)
    {
        throw ex;
    }
}

create table trans(
id bigint identity(1,1) not null,
price decimal(18,0) null,
relatedid bigint null)

Insert into trans (price,relatedid)values(100,NULL) 
Insert into trans (price,relatedid)values(100,NULL) 
Insert into trans (price,relatedid)values(500,NULL)
Insert into trans (price,relatedid)values(1,NULL)
Insert into trans (price,relatedid)values(1,3)   

Update trans
set price=(case when relatedid is null then (select avg(price) from trans where id<=t.id) 
else (select top(1) price from trans where id=t.relatedid) end)
from trans t