File upload control - click and load image immediately

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C#

File-Upload

how can i upload a new image after choosing file and immediately replace the old image?

this is my current code

public partial class AdminEditProduct : System.Web.UI.Page
{
    
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.QueryString.Count != 0)
        {

            int ProductID = Convert.ToInt32(Request.QueryString["ProductID"]);
             

            if (!IsPostBack)
            {
                string strConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
                SqlConnection myConnect = new SqlConnection(strConnectionString);
                SqlCommand cmd = new SqlCommand("SELECT ProductID, ProductName, Price, Description, Sdesc, Picture FROM Product WHERE ProductID=" + ProductID, myConnect);

               
                myConnect.Open();
                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.Read())
                {

                    txtProductName.Text = reader["ProductName"].ToString();
                    txtPrice.Text = reader["Price"].ToString();
                    txtDescription.Text = reader["Description"].ToString();
                    txtSdesc.Text = reader["Sdesc"].ToString();
                    Session["picURL"] =  reader["Picture"].ToString();
                    Image1.ImageUrl = "~/image/" + Session["picURL"].ToString();
                }
                reader.Close();
                myConnect.Close();
            }
        }
    }



    protected void ImageURL(object sender, EventArgs e)
    {
        {
            string picture = Session["Picture"].ToString();
            if ((string.IsNullOrEmpty(picture)))
            {

                string strConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
                SqlConnection myConnect = new SqlConnection(strConnectionString);
                myConnect.Open();

                string strCommandText = "SELECT (Picture) FROM Product";
                SqlCommand cmd = new SqlCommand(strCommandText, myConnect);
                SqlDataReader reader = cmd.ExecuteReader();

                myConnect.Close();

            }
        }
    }

    protected void btnUpdate_Click(object sender, EventArgs e)
    {

        Image1.ImageUrl = null;
        EditDescription();

    }

    private void EditDescription()
    {
        try
        {
            int ProductID = Convert.ToInt32(Request.QueryString["ProductID"]);
            string Description = txtDescription.Text;

            string strConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            SqlConnection myConnect = new SqlConnection(strConnectionString);

            string strCommandText = ("UPDATE Product " + " SET ProductName=@aProductName " + " , Price=@aPrice " + " , Description=@aDescription " + " , Sdesc=@aSdesc " + " , Picture=@aPicture " + "  WHERE ProductID=@aProductID ");

            SqlCommand cmd = new SqlCommand(strCommandText, myConnect);

            cmd.Parameters.Add("@aProductID", SqlDbType.Int).Value = ProductID;
            cmd.Parameters.AddWithValue("@aProductName", txtProductName.Text);
            cmd.Parameters.AddWithValue("@aPrice", Convert.ToDecimal(txtPrice.Text));
            cmd.Parameters.AddWithValue("@aDescription", txtDescription.Text);
            cmd.Parameters.AddWithValue("@aSdesc", txtSdesc.Text);
            if (FileUpload1.FileName != "")
            {
                Session["picURL"] = FileUpload1.FileName;
            }
            cmd.Parameters.AddWithValue("@aPicture", Session["picURL"]);

            myConnect.Open();


            int result = cmd.ExecuteNonQuery();

            myConnect.Close();
            
        }
        catch (Exception e)
        
}