How to store and retrieve a Signature content in SQL database?

<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true"></asp:ScriptManager>
    <div class="frame ">
        <h2>Signature:</h2>
        <div class="control">
           
             <ej:Signature ID="Signature1" Height="400px" StrokeWidth="3" IsResponsive="true" runat="server"></ej:Signature>       // Render signature control
        </div>
 
        <input id="btnUpload" type="button" value="Upload data to Database" onclick="Uploaddata()" /> // Render button for upload data into data base
 
    <input id="btnclear" type="button" value="Clear" onclick="onclear()" />   // Render button for clear the singnature
 
        <input id="btnget" type="button" value="Retrive image from Database" onclick="Getdata()" /> // Render button for get the data from data base
 
    </div>
 
<script>
 
// function to convert the image to Base64 string value and then passing it to the database
        function Uploaddata() {
 
            var target = $("#<%=Signature1.ClientID%>").ejSignature("instance")._canvas[0].toDataURL()
            PageMethods.Upload(target, onSucess, onError); 
 
            function onSucess(response) {
                alert("succesfully sent to datasource")
            }
            function onError(response) {
                alert('Something wrong.');
            }
 
        }
 
// function to retrieve the signature content from the database
        function Getdata() {
            PageMethods.Getuploaddata(onSucess, onError);
 
            function onSucess(response) {
                        var obj = $("#<%=Signature1.ClientID%>").ejSignature("instance");  // Create object for signature control
                        canvas = obj._canvas[0];
                        ctx = canvas.getContext("2d");
                        var img = new Image;
                        img.src = response;
                        ctx.clearRect(0, 0, canvas.width, canvas.height);  // Clear specified pixel
                        ctx.drawImage(img, 0, 0);  
                        obj.refresh();
            }
            function onError(response) {
                alert('Something wrong.');
            }
        }
 
   function onclear() {    // Triggered when you click the clear button
           var obj = $("#<%=Signature1.ClientID%>").ejSignature("instance");  // Created object for signature control
           obj.clear();    // Clear the signature control using clear public method
      }
    </script>

// method to store the signature content in the database table
 
[System.Web.Services.WebMethod]
        public static string Upload(string target)
        {
            // Convert string into stream
            var stream = new MemoryStream();
            var writer = new StreamWriter(stream);
            writer.Write(target);
            writer.Flush();
            stream.Position = 0;
            SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\David\WebSample\App_Data\Signaturedata.mdf;Integrated Security=True;Connect Timeout=30");  // Set your system local database file location
            con.Open();
            string query = "INSERT INTO newData (DataValue) VALUES ('" + stream+ "')";
            SqlCommand cmd = new SqlCommand(query);
            cmd.Connection = con;
            cmd.ExecuteNonQuery();
            con.Close();
            return target;
        }
 
// method to retrieve the stored signature content from database
        [System.Web.Services.WebMethod]
        public static string Getuploaddata()
        {
            using (SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename= D:\David\WebSample\App_Data\Signaturedata.mdf;Integrated Security=True;Connect Timeout=30")) // Your database path
            using (SqlCommand command = new SqlCommand("SELECT DataValue FROM newData"))
            {
                command.Connection = conn;
                conn.Open();
                SqlDataReader reader = command.ExecuteReader();
                if (reader.Read())
                {
                    return reader.GetString(0);
                }
                return null;
            }
        }