C#

public partial class Lab_frmLabBilling : System.Web.UI.Page
{
    DataSet dsBill = new DataSet();
    DataTable dtBill = new DataTable("LabBill");
    
    protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
            if (!Page.IsPostBack)
            {            

                InitializeDS();                 
            }          
        }
        catch (Exception ex)
        {
            Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "HMS", ex.Message, false);
        }
    }

private void InitializeDS()
    {
        try
        {
            DataColumn dCol1 = new DataColumn("Lab_SNo",typeof(int));
            DataColumn dCol2 = new DataColumn("pk_lab_bill_id",typeof(int));
            DataColumn dCol3 = new DataColumn("GroupId",typeof(int));
            DataColumn dCol4 = new DataColumn("TestId",typeof(int));
            DataColumn dCol5 = new DataColumn("Lab_Test", typeof(string));
            DataColumn dCol6 = new DataColumn("Lab_Test_Cost", typeof(float));

            dtBill.Columns.Add(dCol1);
            dtBill.Columns.Add(dCol2);
            dtBill.Columns.Add(dCol3);
            dtBill.Columns.Add(dCol4);
            dtBill.Columns.Add(dCol5);
            dtBill.Columns.Add(dCol6);
            
            dsBill.Tables.Add(dtBill);

        }
        catch (Exception ex)
        {
            Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "HMS", ex.Message, false);
        }
    }

protected void btnGInsert_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtGroupName.Text == string.Empty)
            {
                Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "HMS", "Please Enter Group Name", false);
                return;
            }

            int iCount;

            iCount = dtBill.Columns.Count;
            iCount = dtBill.Rows.Count;            

            iCount++;

            DataRow drBill;

           
            drBill = dtBill.NewRow();
            drBill["Lab_SNo"] = iCount;
            drBill["pk_lab_bill_id"] = iCount;
            drBill["GroupId"] = int.Parse(Session["LabGroupId"].ToString());
            drBill["TestId"] = 0;
            drBill["Lab_Test"] = txtGroupName.Text;
            drBill["Lab_Test_Cost"] = float.Parse(Session["TestCost"].ToString());
            dtBill.Rows.Add(drBill);

            dsBill.AcceptChanges();

            grdLabBill.DataSource = dsBill;
            grdLabBill.DataBind();

            txtGroupName.Text = "";
            Session["GroupId"] = 0;
        }
        catch (Exception ex)
        {
            Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "HMS", ex.Message, false);
        }
    }
}