Save files in database site and retrieve files

 ======Aspx =========
<form id="form1" runat="server">
    <div>
        <asp:Button ID="Button1" runat="server" Text="InsertDoc" OnClick="InsertDoc_Click" />
        <asp:Button ID="Button2" runat="server" Text="InsertXls" OnClick="InsertXls_Click" />
        <asp:Button ID="Button3" runat="server" Text="InsertImage" OnClick="InsertImage_Click" />
        <asp:Button ID="Button4" runat="server" Text="InsertPdf" OnClick="InsertPdf_Click" /><br /><br />
        <asp:LinkButton ID="LinkButton1" runat="server" OnClick = "Retreive_Doc">Download Doc</asp:LinkButton>
        <asp:LinkButton ID="LinkButton2" runat="server" OnClick = "Retreive_Xls">Download xls</asp:LinkButton>
        <asp:LinkButton ID="LinkButton3" runat="server" OnClick = "Retreive_Image">Download Image</asp:LinkButton>
        <asp:LinkButton ID="LinkButton4" runat="server" OnClick = "Retreive_Pdf">Download Pdf</asp:LinkButton>
    </div>
    </form>
======c sharp code=========
using System;
using System.Data;
using System.Data.SqlClient ;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Drawing.Imaging;
using System.Drawing;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
     
    }
 
    protected void InsertDoc_Click(object sender, EventArgs e)
    {
        // Read the file and convert it to Byte Array
        string filePath = Server.MapPath("APP_DATA/TestDoc.docx");
        string filename = Path.GetFileName(filePath);

        FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
        BinaryReader br = new BinaryReader(fs);
        Byte[] bytes = br.ReadBytes((Int32)fs.Length);
        br.Close();
        fs.Close();

        //insert the file into database
        string strQuery = "insert into tblFiles(Name, ContentType, Data) values (@Name, @ContentType, @Data)";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar).Value = filename;
        cmd.Parameters.Add("@ContentType", SqlDbType.VarChar).Value = "application/vnd.ms-word";
        cmd.Parameters.Add("@Data", SqlDbType.Binary).Value = bytes;
        InsertUpdateData(cmd);
    }
    protected void InsertXls_Click(object sender, EventArgs e)
    {
        // Read the file and convert it to Byte Array
        string filePath = Server.MapPath("APP_DATA/Testxls.xlsx");
        string filename = Path.GetFileName(filePath);

        FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
        BinaryReader br = new BinaryReader(fs);
        Byte[] bytes = br.ReadBytes((Int32)fs.Length);
        br.Close();
        fs.Close();

        //insert the file into database
        string strQuery = "insert into tblFiles(Name, ContentType, Data) values (@Name, @ContentType, @Data)";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar).Value = filename;
        cmd.Parameters.Add("@ContentType", SqlDbType.VarChar).Value = "application/vnd.ms-excel";
        cmd.Parameters.Add("@Data", SqlDbType.Binary).Value = bytes;
        InsertUpdateData(cmd);
    }
    protected void InsertImage_Click(object sender, EventArgs e)
    {
        // Read the file and convert it to Byte Array
        string filePath = Server.MapPath("APP_DATA/TestImage.jpg");
        string filename = Path.GetFileName(filePath);

        FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
        BinaryReader br = new BinaryReader(fs);
        Byte[] bytes = br.ReadBytes((Int32)fs.Length);
        br.Close();
        fs.Close();

        //insert the file into database
        string strQuery = "insert into tblFiles(Name, ContentType, Data) values (@Name, @ContentType, @Data)";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar).Value = filename;
        cmd.Parameters.Add("@ContentType", SqlDbType.VarChar).Value = "image/jpeg";
        cmd.Parameters.Add("@Data", SqlDbType.Binary).Value = bytes;
        InsertUpdateData(cmd);
    }

    protected void InsertPdf_Click(object sender, EventArgs e)
    {
        // Read the file and convert it to Byte Array
        string filePath = Server.MapPath("APP_DATA/TestPdf.pdf");
        string filename = Path.GetFileName(filePath);

        FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
        BinaryReader br = new BinaryReader(fs);
        Byte[] bytes = br.ReadBytes((Int32)fs.Length);
        br.Close();
        fs.Close();

        //insert the file into database
        string strQuery = "insert into tblFiles(Name, ContentType, Data) values (@Name, @ContentType, @Data)";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar).Value = filename;
        cmd.Parameters.Add("@ContentType", SqlDbType.VarChar).Value = "application/pdf";
        cmd.Parameters.Add("@Data", SqlDbType.Binary).Value = bytes;
        InsertUpdateData(cmd);
    }

    protected void Retreive_Doc(object sender, EventArgs e)
    {
        string strQuery = "select Name, ContentType, Data from tblFiles where id=@id";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@id", SqlDbType.Int).Value = 1;
        DataTable dt = GetData(cmd);
        if (dt != null)
        {
            download(dt);
        }
    }
    protected void Retreive_Xls(object sender, EventArgs e)
    {
        string strQuery = "select Name, ContentType, Data from tblFiles where id=@id";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@id", SqlDbType.Int).Value = 2;
        DataTable dt = GetData(cmd);
        if (dt != null)
        {
            download(dt);
        }
    }
    protected void Retreive_Image(object sender, EventArgs e)
    {
        string strQuery = "select Name, ContentType, Data from tblFiles where id=@id";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@id", SqlDbType.Int).Value = 1;
        DataTable dt = GetData(cmd);
        if (dt != null)
        {
            download(dt);
        }
    }

    protected void Retreive_Pdf(object sender, EventArgs e)
    {
        string strQuery = "select Name, ContentType, Data from tblFiles where id=@id";
        SqlCommand cmd = new SqlCommand(strQuery);
        cmd.Parameters.Add("@id", SqlDbType.Int).Value = 4;
        DataTable dt = GetData(cmd);
        if (dt != null)
        {
            download(dt);
        }
    }

    private Boolean InsertUpdateData(SqlCommand cmd)
    {
        String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
        SqlConnection con = new SqlConnection(strConnString);
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;
        try
        {
            con.Open();
            cmd.ExecuteNonQuery();
            return true;
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
            return false;
        }
        finally
        {
            con.Close();
            con.Dispose();
        }
    }

    private DataTable GetData(SqlCommand cmd)
    {
        DataTable dt = new DataTable();
        String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
        SqlConnection con = new SqlConnection(strConnString);
        SqlDataAdapter sda = new SqlDataAdapter();
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;
        try
        {
            con.Open();
            sda.SelectCommand = cmd;
            sda.Fill(dt);
            return dt;
        }
        catch
        {
            return null;
        }
        finally
        {
            con.Close();
            sda.Dispose();
            con.Dispose();
        }
    }

    private void download (DataTable dt)
    {
        Byte[] bytes = (Byte[])dt.Rows[0]["Data"];
        Response.Buffer = true;
        Response.Charset = "";
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        Response.ContentType = dt.Rows[0]["ContentType"].ToString();
        Response.AddHeader("content-disposition", "attachment;filename="
        + dt.Rows[0]["Name"].ToString());
        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.End();
    }

 
}

======web config=========

<connectionStrings>

    <add name="conString" connectionString="Data Source=server;database=dbFiles;uid=sa;pwd=Admin@123"/>

  </connectionStrings >

=====Db==============

/****** Object:  Table [dbo].[tblFiles]    Script Date: 11/19/2015 11:43:46 AM ******/

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

SET ANSI_PADDING ON

GO

CREATE TABLE [dbo].[tblFiles](

[Id] [int] IDENTITY(1,1) NOT NULL,

[Name] [nvarchar](50) NULL,

[ContentType] [nvarchar](50) NULL,

[Data] [varbinary](max) NULL

) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

SET ANSI_PADDING OFF

GO