After insert my discount is changed in asp.net

Question

private void BindListView()

{

string constr = ConfigurationManager.AppSettings["s"].ToString();

using (SqlConnection con = new SqlConnection(constr))

{

using (SqlCommand cmd = new SqlCommand())

{

using (SqlDataAdapter sda = new SqlDataAdapter(cmd))

{

cmd.CommandText = "select distinct sectionname,lotno,Productname,mrp from purchase where lotno='" + txtBarcode.Text + "'";

cmd.Connection = con;

// DataTable dt = new DataTable();

using (DataTable dt = new DataTable())

{

sda.Fill(dt);

DataTable products = new DataTable();

if (ViewState["Products"] == null)

{

products.Merge(dt, true);

}

else

{

products = (DataTable)ViewState["Products"];

products.Merge(dt, true);

}

ViewState["Products"] = products;

ddsales.DataSource = products;

ddsales.DataBind();

double total = dt.AsEnumerable().Sum(row => row.Field<double>("mrp"));

ddsales.FooterRow.Cells[3].Text = "Total";

ddsales.FooterRow.Cells[1].HorizontalAlign = HorizontalAlign.Right;

ddsales.FooterRow.Cells[4].Text = total.ToString("N2");

}

}

}

}

txtBarcode.Text = "";

txtBarcode.Focus();

}

 

 

 

protected void txtdispr_TextChanged(object sender, EventArgs e)

{

if (txtdispr.Text != "")

{

foreach (GridViewRow gvr in this.ddsales.Rows)

{

if (((CheckBox)gvr.FindControl("chkSelect")).Checked == true)

{

string bqno = (gvr.FindControl("lblmrp") as Label).Text;

double dis, mmr, pmr, totdis, nowdis;

dis = int.Parse(txtdispr.Text);

mmr = int.Parse(bqno);

pmr = dis * mmr;

totdis = pmr / 100;

nowdis = mmr - totdis;

(gvr.FindControl("lblmrp") as Label).Text = Convert.ToString(nowdis);

}

txtdispr.Text = "";

break;

}

}

else

{

txtdispr.Focus();

}

}

 

http://s280.photobucket.com/user/celvsubramanian/library/

in this it shows the discount