Retrieve pdf file from sql c#

Question

Some help please

 

Insert into sql

 

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();



                       }

                   }
               }

 

 In Selection change datagrid put this

 

try
                {
                     if (documentsDataGridView.SelectedRows[0].Cells["pdf_file"].Value != null)
                     {
                        byte[] ap = (byte[])documentsDataGridView.SelectedRows[0].Cells["pdf_file"].Value;
                        MemoryStream ms = new MemoryStream(ap);
                        axAcroPDF1.src = LocalEncoding.GetString(ms.ToArray());

                    }
                    else {
                         axAcroPDF1.src = null;
                     }
                }
                catch
                {
                    axAcroPDF1.src = null;
                }

 Error is when retrieve file...(no have error) noting hapend....what I wrong?

 

I think at line 3 to line 9