private string sqlconnstr = "Data Source=.;Database=db_test;User id=sa;PWD=123456";
/*功能：把一种图片插入到数据库中
 *返回值：无
 */
void InsertImageToDB()
{
  //将需要存储的图片读取为数据流
  FileStream fs = new FileStream(@"D:/Bear.jpg", FileMode.Open, FileAccess.Read);
  Byte[] byte_fs = new byte[fs.Length];
  fs.Read(byte_fs, 0, Convert.ToInt32(fs.Length));
  fs.Close();
  //建立数据库连接
  SqlConnection conn = new SqlConnection(sqlconnstr);
  conn.Open();
  SqlCommand cmd = new SqlCommand();
  cmd.Connection = conn;
  cmd.CommandText = "insert into tb_test(image_id,image_file) values(@image_id,@image_file)";
  SqlParameter[] param = new SqlParameter[2];
  param[0] = new SqlParameter("@image_id", SqlDbType.Int);
  param[0].Value = 1;
  param[1] = new sqlParameter("@image_file", SqlDbType.Image);
  param[1].Value = byte_fs;
  for (int index = 0; index < 2; index++)
  {
 cmd.Parameters.Add(param[i]);
  }
  //执行SQL语句
  cmd.ExecuteNonQuery();
  conn.Close();
}
/*功能：从数据库中读取图像文件，并显示在PictureBox控件中
 *返回值：无
 */
void GetImageFromDB()
{
  byte[] Data = new byte[0];
  //建立数据库连接
  SqlConnection conn = new SqlConnection(sqlconnstr);
  conn.Open();
  SqlCommand cmd = new SqlCommand();
  cmd.Connection = conn;
  cmd.CommandText = "select * from tb_parent";
  SqlDataReader sdr = cmd.ExecuteReader();
  sdr.Read();
  Data = (byte[])sdr["parent_image"];//读取第一个图片的位流
  MemoryStream mystream = new MemoryStream(Data);
  //用指定的数据流来创建一个image图片
  System.Drawing.Image picbImage = System.Drawing.Image.FromStream(mystream, true);
  mystream.Close();
  picturebox1.Image = picbImage;
  conn.Close();
}