protected void DataSet1Button_Click(object sender, EventArgs e)
{
    this.ReportViewer1.Reset();
    this.ReportViewer1.ProcessingMode = ProcessingMode.Local;
    this.ReportViewer1.LocalReport.DataSources.Clear();

    DataTable dt1 = getDataSet1Data();
    ReportDataSource datasource = new ReportDataSource("DataSet1", dt1);
    this.ReportViewer1.LocalReport.DataSources.Add(datasource);
    this.ReportViewer1.LocalReport.ReportPath = (@"...mypath...MyApp7Report1.rdlc");

    this.ReportViewer1.LocalReport.Refresh();
    this.ReportViewer1.Visible = true;

}

protected void DataSet2Button_Click(object sender, EventArgs e)
{
    this.ReportViewer1.Reset();
    this.ReportViewer1.ProcessingMode = ProcessingMode.Local;
    this.ReportViewer1.LocalReport.DataSources.Clear();

    DataTable dt2 = getDataSet2Data();
    ReportDataSource datasource2 = new ReportDataSource("DataSet2", dt2);
    this.ReportViewer1.LocalReport.DataSources.Add(datasource2);
    this.ReportViewer1.LocalReport.ReportPath = (@"...mypath...MyApp7Report2.rdlc");

    this.ReportViewer1.LocalReport.Refresh();
    this.ReportViewer1.Visible = true;

}

public DataTable getDataSet1Data()
{
    string constring = "Data Source = x.x.x.x; Initial Catalog = Adventureworks2014; Integrated Security = SSPI";
    using (SqlConnection sqlconn = new SqlConnection(constring))
    {
        string commandText = "SELECT ProductID, Name, ProductNumber, MakeFlag, FinishedGoodsFlag, Color, SafetyStockLevel, ReorderPoint, StandardCost, ListPrice, Size, SizeUnitMeasureCode, WeightUnitMeasureCode, Weight, DaysToManufacture, ProductLine, Class, Style, ProductSubcategoryID, ProductModelID, SellStartDate, SellEndDate, DiscontinuedDate, rowguid, ModifiedDate FROM Production.Product";
        using (SqlCommand sqlcomm = new SqlCommand(commandText, sqlconn))
        {
            using (SqlDataAdapter sqladap = new SqlDataAdapter(sqlcomm))
            {
                using (DataSet1 dset1 = new DataSet1())
                {
                    sqladap.Fill(dset1, dset1.Product.TableName);
                    return dset1.Product;
                }
            }
        }
    }
}
public DataTable getDataSet2Data()
{
    string constring = "Data Source = x.x.x.x; Initial Catalog = Adventureworks2014; Integrated Security = SSPI";
    using (SqlConnection sqlconn = new SqlConnection(constring))
    {
        string commandText = "SELECT PurchaseOrderID, PurchaseOrderDetailID, OrderQty, ProductID, ReceivedQty, RejectedQty, StockedQty FROM Purchasing.PurchaseOrderDetail";
        using (SqlCommand sqlcomm = new SqlCommand(commandText, sqlconn))
        {
            using (SqlDataAdapter sqladap = new SqlDataAdapter(sqlcomm))
            {
                using (DataSet2 dset2 = new DataSet2())
                {
                    sqladap.Fill(dset2, dset2.PurchaseOrderDetail.TableName);
                    return dset2.PurchaseOrderDetail;
                }
            }
        }
    }