Retrieve pdf or doc files from sqldatabase

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
    <columns>
        <asp:BoundField DataField="Section" HeaderText="File Name" />
        <asp:BoundField DataField="Category" HeaderText="File Name" />
        <asp:TemplateField ItemStyle-HorizontalAlign="Center">
            <itemtemplate>
               
                 <asp:LinkButton ID="lnkView" OnClick="OpenDocument" runat="server" Text='<%# Eval("Link") %>'>

protected void OpenDocument(object sender, EventArgs e)
{
    LinkButton lnk = (LinkButton)sender;
    GridViewRow gr = (GridViewRow)lnk.NamingContainer;
    if (gr.RowIndex > 0)
    { 
    int id = int.Parse(GridView1.DataKeys[gr.RowIndex].Value.ToString());
    Download(id);
    }
}
private void Download(int id)
{
    DataTable dt = new DataTable();
    string constr = ConfigurationManager.ConnectionStrings["IntranetConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "SELECT Seqn, Section, Category, Link from Links WHERE Seqn = @seqn ";
            cmd.Connection = con;
            cmd.Parameters.Add("@seqn", SqlDbType.Int).Value = id;
            con.Open();
            SqlDataReader reader = cmd.ExecuteReader();

            dt.Load(reader);
        }
    }
    string name = dt.Rows[0]["Category"].ToString();
    byte[] documentBytes = (byte[])dt.Rows[0]["Link"];
    Response.ClearContent();
    Response.ContentType = "application/octetstream";
    Response.AddHeader("Content-Disposition", string.Format("attachment; filename={}", name));
    Response.AddHeader("Content-Length", documentBytes.Length.ToString());

    Response.BinaryWrite(documentBytes);
    Response.Flush();
    Response.Close();
 }
private void FillData()
{
    DataTable dt = new DataTable();
    string constr = ConfigurationManager.ConnectionStrings["IntranetConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "SELECT Seqn, Section, Category, Link from Links ";
            cmd.Connection = con;
            con.Open();
            SqlDataReader reader = cmd.ExecuteReader();
           
            dt.Load(reader);
          
            con.Close();
        }
        if (dt.Rows.Count > 0)
        {
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
    }
}