Insert TextBox value into GridView fetching from Database using C# in ASP.Net

i am retrieving data into textbox, now i want when data called into textbox then auto insert into gridview.

        protected void btnClear_Click(object sender, EventArgs e)
        {  
            insertintopacktxt();
        }

        private void insertintopacktxt()
        {
            String strQuery = "select MAX(PID) as PID from tbl_BalPacM" ;
            // SqlConnection con = new SqlConnection();
            SqlCommand cmde = new SqlCommand();
            cmde.Parameters.AddWithValue("@PID", txtsearcbn.Text);
            cmde.CommandType = CommandType.Text;
            cmde.CommandText = strQuery;
            cmde.Connection = con;
            try
            {
                con.Open();
                SqlDataReader sdr = cmde.ExecuteReader();
                while (sdr.Read())
                {                  
                    txtsearcbn.Text = sdr["PID"].ToString();                   
                }
            }
            catch (Exception ex)
            {
                //throw ex;
            }
            con.Close();
        }        
    }