C#保存文件或读取数据库文件 另存为

/// <summary>
        /// 保存文件到数据库
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {
            string conn = @"Data Source=YANGYIBANG\SQLEXPRESS;Initial Catalog=joe;Integrated Security=True";
            SqlConnection cn = new SqlConnection(conn);
            Stream myStream = null;
            OpenFileDialog openFileDialog1 = new OpenFileDialog();

            //openFileDialog1.InitialDirectory = "c:\\";
            //openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
            //openFileDialog1.FilterIndex = 2;
            openFileDialog1.RestoreDirectory = true;

            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    FileInfo fi = new FileInfo(openFileDialog1.FileName);
                    FileStream fs = fi.OpenRead();
                    byte[] bytes = new byte[fs.Length];
                    fs.Read(bytes, 0, Convert.ToInt32(fs.Length));
                    SqlCommand cm = new SqlCommand();
                    cm.Connection = cn;
                    cm.CommandType = CommandType.Text;
                    if (cn.State == 0) cn.Open();
                    cm.CommandText = "insert into title (titileName, files ) values('aaa',@file)";
                    SqlParameter spFile = new SqlParameter("@file", SqlDbType.Image);
                    spFile.Value = bytes;
                    cm.Parameters.Add(spFile);
                    cm.ExecuteNonQuery();
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
                }
            }

            

        }


        /// <summary>
        /// 从数据库就读取文件另存为
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {
            try
            {

            
            string conn = @"Data Source=YANGYIBANG\SQLEXPRESS;Initial Catalog=joe;Integrated Security=True";
            SqlConnection cn = new SqlConnection(conn);
            SqlDataReader dr = null;
            SqlCommand cm = new SqlCommand();
            cm.Connection = cn;
            cm.CommandType = CommandType.Text;
            cm.CommandText = "select  files  from title where titileId=5";
            cn.Open();
            dr = cm.ExecuteReader();
            byte[] File = null;
            if (dr.Read())
            {
                File = (byte[])dr[0];
            }

            dr.Close();
            cn.Close();
          
                /*
                 * 直接另存为文件
                 * 
                 */ 
            SaveFileDialog saveFileDialog1 = new SaveFileDialog();
            Stream myStream;

            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                if ((myStream = saveFileDialog1.OpenFile()) != null)
                {
                    using (BinaryWriter bw = new BinaryWriter(myStream))
                    {
                        // Add some text to the file.
                        bw.Write(File);
                    }

                }
            }
                
           
            }
            catch (Exception ex)
            {

                MessageBox.Show("Error: Could not read file from db. Original error: " + ex.Message);
            }
        }