Select Varbinary or Image form MSSQL dtabase

protected void ddlImages_SelectedIndexChanged(object sender, EventArgs e)
        {
            string id = ddlImages.SelectedItem.Value;
            Image1.Visible = id != "0";
            if (id != "0")
            {
                byte[] bytes = (byte[])GetData("SELECT Data FROM Images WHERE Id =" + id).Rows[0]["Data"];
                string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);
                Image1.ImageUrl = "data:image/png;base64," + base64String;
            }
        }

        private DataTable GetData(string query)
        {
            DataTable dt = new DataTable();
            string constr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            using (SqlConnection con = new SqlConnection(constr))
            {
                using (SqlCommand cmd = new SqlCommand(query))
                {
                    using (SqlDataAdapter sda = new SqlDataAdapter())
                    {
                        cmd.CommandType = CommandType.Text;
                        cmd.Connection = con;
                        sda.SelectCommand = cmd;
                        sda.Fill(dt);
                    }
                }
                return dt;
            }
        }