Regarding to ask a Question

to uplaod file on server

protected void btnSub_Click(object sender, EventArgs e)
    {
        try
        {
            string filename = FileUpload1.FileName;
            string filename1 = FileUpload2.FileName;
            FileUpload1.PostedFile.SaveAs(Server.MapPath("~\\Uploadform\\" + filename.Trim()));
            FileUpload2.PostedFile.SaveAs(Server.MapPath("~\\Uploadform\\" + filename1.Trim()));
            string path = "~\\Uploadform\\" + filename.Trim();
            string path1 = "~\\Uploadform\\" + filename1.Trim();
            SqlConnection con = new SqlConnection(str);
            cmd = new SqlCommand("Insert into Circular(title,type,url1,url2) values('" + txttitle.Text + "','" + txttype.Text + "','" + path + "','" + path1 + "')", con);
            lblinfo.Text = " Uploaded Successfully ";
            cmd.CommandType = CommandType.Text;
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
    }

your file can be simply download/open as

Response.Redirect(pdfurlfetchfromdatabase);

Means you need to store a file in Database ? if i am roght then here read the following.

To store a file in database you need to convert it to ByteArray[]. You can use dataType as Image, Vatbinary.

To download file from database, you need to read ByteArray and write it on pdf file using
system.Io.WriteAllBytes()

here is link[^] for your help.