C# MS SQL Server 获取数据库中的图片

Question

        public static SqlConnection connection = new SqlConnection("server=.; database=FilmDirectory; Integrated Security=true");        public static Bitmap GetPicture(int i)
        {
            byte[] imageByte = null;            string sql = "select Image from film where ID=" + i;
            connection.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = sql;
            cmd.Connection = connection;            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                imageByte = (byte[])dr[0];           
            }            dr.Close();
            connection.Close();
            MemoryStream ms = new MemoryStream(imageByte, true);
            Bitmap bmpt = new Bitmap(ms);
            return bmpt;
        }
这段代码中老是出现“参数无效”的错误。错误指向红色部分，不知何解。请赐教！-----------------------------------------------------------------------------------------
        public static SqlConnection connection = new SqlConnection("server=.; database=FilmDirectory; Integrated Security=true");.................
 string sqlStr = "select top 3 * from film";
            DataSet ds = new DataSet();
            ds = GetDataFromDB(sqlStr);
            if (ds != null)
            {
                for (int i = 1; i <= ds.Tables[0].Rows.Count; i++)
                {
                    switch (i)
                    {
                        case 1:
                            ................
                            pictureBox1.Image = Image.FromStream(new MemoryStream((byte[])(ds.Tables[0].Rows[0].ItemArray[7])));                           
                       break;这是用DataSet数据集的方式访问数据库，但是还是会出现相同的错误。高手们请赐教！

Answer 1

 object obj=new object();
obj=数据库读取的二进制数据； Byte[] byt = new Byte[0];
                    byt = (Byte[])(obj);
                    System.IO.MemoryStream stm = new System.IO.MemoryStream(byt);
                    System.Drawing.Image image = System.Drawing.Image.FromStream(stm);

Answer 2

MemoryStream ms=new MemoryStream((byte[])reader["Photo"]);   
  Image image=Image.FromStream(ms,true);   
  picturebox1.Image=image;   
 检查数据长度