Вставить PDF файл в базу данных C#

private void Button2_Click(object sender, EventArgs e)   //Save pdf in database
        {
            byte[] filedata = null;
            MemoryStream ms = new MemoryStream();
            filedata = ms.GetBuffer();
            axAcroPDF1.src = LocalEncoding.GetString(ms.ToArray());



                    using (SqlConnection openCon = new SqlConnection(cs))
                    {

                        string saveStaff = "declare @maxNo integer = 0 select @maxNo = isnull(max(number), 0) from [dbo].[documents]; Set @maxNo=@maxNo+1; INSERT into dbo.documents (number,file_location, pdf_file) VALUES (@maxNo,@file_location,@pdf_file)";

                        using (SqlCommand querySaveStaff = new SqlCommand(saveStaff))
                        {
                            querySaveStaff.Connection = openCon;

                            querySaveStaff.Parameters.Add("@file_location", SqlDbType.VarChar, 255).Value = file_locationTextBox.Text;

                            querySaveStaff.Parameters.AddWithValue("@pdf_file", SqlDbType.VarBinary).Value = filedata;

                            openCon.Open();
                            querySaveStaff.ExecuteNonQuery();
                            openCon.Close();                            


                        }

                    }

}