Updation of data in asp.net ,c#,Ms-Access

See more:

C#

ASP.NET

MS-Access

Hello frndz , I m trying to update the data from my asp.net form
I m having gridview ,wwhen i clik on particular row in grid view it displays all the data into
respective texboxes. I want to update this data .I tried to write a query but it showed me an error.
Here i my full code of c#

public partial class Company_Master : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            lbluser.Text = Session["user_id"].ToString();
            lbldiv.Text = Session["division_id"].ToString();
            lblunit.Text = Session["unitcode"].ToString();
            lblloyr.Text = Session["year"].ToString();
            lbldate.Text = Session["date"].ToString();
        }

        Util.JQueryUtils.RegisterTextBoxForDatePicker(Page, txtregdt);
        DataTable dt;
        OleDbConnection conn = new OleDbConnection(ConfigurationManager.ConnectionStrings["vhgroupconnection"].ConnectionString);
        OleDbCommand cmd1 = new OleDbCommand("SELECT cmp_id,cmp_name,reg_no,reg_dt,addr_line_1,addr_line_2,addr_line_3,pin_code,lst_no,cst_no,fax,phone,emailid FROM company_master ORDER BY cmp_id ASC", conn);
        OleDbDataAdapter dA = new OleDbDataAdapter(cmd1);
        dt = new DataTable();
        dA.Fill(dt);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        Session["comp"] = dt;
        GridView1.Visible = true;
        
    }
    protected void btnadd_Click(object sender, EventArgs e)
    {
        try
        {
            OleDbConnection myConnection = new OleDbConnection(ConfigurationManager.ConnectionStrings["vhgroupconnection"].ConnectionString);
            string query = "INSERT INTO company_master(cmp_id,cmp_name,reg_no,reg_dt,addr_line_1,addr_line_2,addr_line_3,pin_code,lst_no,cst_no,fax,phone,emailid) VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?)";
            using (myConnection)
            {
                myConnection.Open();
                using (OleDbCommand cmd = new OleDbCommand(query, myConnection))
                {
                    cmd.CommandType = CommandType.Text;
                    cmd.Parameters.AddWithValue("cmp_id", txtcompid.Text);
                    cmd.Parameters.AddWithValue("cmp_name", txtcompname.Text);
                    cmd.Parameters.AddWithValue("reg_no", txtregno.Text);
                    cmd.Parameters.AddWithValue("reg_dt", DateFormat.SplitDateStringAndReturnObject(txtregdt.Text));
                    cmd.Parameters.AddWithValue("addr_line_1", txtaddr.Text);
                    cmd.Parameters.AddWithValue("addr_line_2", txtaddr1.Text);
                    cmd.Parameters.AddWithValue("addr_line_3", txtaddr2.Text);
                    cmd.Parameters.AddWithValue("pin_code" ,txtpin.Text);
                    cmd.Parameters.AddWithValue("lst_no",txtlocalsale.Text);
                    cmd.Parameters.AddWithValue("cst_no",txtcentraltxt.Text);
                    cmd.Parameters.AddWithValue("fax", txtfax.Text);
                    cmd.Parameters.AddWithValue("phone", txtphone.Text);
                    cmd.Parameters.AddWithValue("emailid", txtemail.Text);

                    cmd.ExecuteNonQuery();
                }
                myConnection.Close();
            }

        }
        catch (Exception ex)
        {
            Response.Write("Error In An Application :" + ex.StackTrace + ex.Message);
        }
    }
    
    private class DateFormat
    {
        public static DateTime SplitDateStringAndReturnObject(string DateString)
        {
            if (DateString == "" || DateString == null)
            {

                int year = 9999;
                int month = 1;
                int day = 1;
                DateTime dtObj = new DateTime(year, month, day);
                return dtObj;
            }
            else
            {
                int len;
                string[] datesplit = DateString.Split('-');
                len = datesplit.Length;
                if (len < 3)
                {
                    datesplit = DateString.Split('/');
                }

                int year = Convert.ToInt32(datesplit[2]);
                int month = Convert.ToInt32(datesplit[1]);
                int day = Convert.ToInt32(datesplit[0]);
                DateTime dtObj = new DateTime(year, month, day);
                return dtObj;
            }

        }
    }

    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        txtcompid.Text = GridView1.SelectedDataKey.Values[0].ToString();
        txtcompname.Text = GridView1.SelectedDataKey.Values[1].ToString();
        txtregno.Text = GridView1.SelectedDataKey.Values[2].ToString();
        txtregdt.Text = GridView1.SelectedDataKey.Values[3].ToString();
        txtaddr.Text = GridView1.SelectedDataKey.Values[4].ToString();
        txtaddr1.Text = GridView1.SelectedDataKey.Values[5].ToString();
        txtaddr2.Text = GridView1.SelectedDataKey.Values[6].ToString();
        txtpin.Text = GridView1.SelectedDataKey.Values[7].ToString();
        txtlocalsale.Text = GridView1.SelectedDataKey.Values[8].ToString();
        txtcentraltxt.Text = GridView1.SelectedDataKey.Values[9].ToString();
        txtfax.Text = GridView1.SelectedDataKey.Values[10].ToString();
        txtphone.Text = GridView1.SelectedDataKey.Values[11].ToString();
        txtemail.Text = GridView1.SelectedDataKey.Values[12].ToString();
    }
    protected void btnupdate_Click(object sender, EventArgs e)
    {
        try
        {
            OleDbConnection con = new OleDbConnection(ConfigurationManager.ConnectionStrings["vhgroupconnection"].ConnectionString);
            OleDbCommand cmd = new OleDbCommand("UPDATE company_master SET cmp_name = '" + txtcompname.Text + "',reg_no = '" + txtregno.Text + "',reg_dt ='" + 

DateFormat.SplitDateStringAndReturnObject(txtregdt.Text) + "',addr_line_1 = '" + txtaddr.Text 

+ "',addr_line_2 = '" + txtaddr1.Text + "',addr_line_3 = '" + txtaddr2.Text + "',pin_code = '" 

+ txtpin.Text + "',lst_no = '" + txtlocalsale.Text + "',cst_no ='" + txtcentraltxt.Text + 

"',phone = '" + txtphone.Text + "',email ='" + txtemail.Text + "' WHERE cmp_id ='" + 

txtcompid.Text + "'", con);
            con.Open();
            cmd.CommandType = CommandType.Text;
            OleDbDataAdapter da = new OleDbDataAdapter(cmd);
            cmd.CommandType = CommandType.Text; 
            cmd.ExecuteNonQuery();
            Response.Write("Update Success");
            con.Close();
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
    }
}

Please help me to write the query

after updation gridvew should also be updated