mysql存储图片的问题 - .NET技术 / C#

把图片存入到mysql中：
  DateTime dt = (DateTime)para[0];
  string plateNo = (string)para[1];
  byte[] photo = (byte[])para[2];

  string sqlString = "insert into table1(Time,PlateNo,PlateImg) VALUES(?dt,?plateNo,?photo)";

  MySQLCommand dbCommand = new MySQLCommand();
  dbCommand.Connection = dbConnection;
  dbCommand.CommandText = sqlString;
  dbCommand.CommandType = System.Data.CommandType.Text;

  MySQLParameter mp1 = new MySQLParameter("?dt", System.Data.DbType.DateTime);
  mp1.Value = dt;
  dbCommand.Parameters.Add(mp1);
  MySQLParameter mp2 = new MySQLParameter("?plateNo", System.Data.DbType.String);
  mp2.Value = plateNo;
  dbCommand.Parameters.Add(mp2);
  MySQLParameter mp3 = new MySQLParameter("?photo", System.Data.DbType.Binary);
  mp3.Value = photo;
  dbCommand.Parameters.Add(mp3);
  MessageBox.Show("photo length:" + ((byte[])(mp3.Value)).Length.ToString());
  dbCommand.ExecuteNonQuery();
把图片读出来：
  byt