誤差的圖像DATATYPES

Question

An unhandled exception of type 'System.InvalidCastException' occurred in WindowsFormsApplication1.exe and Additional information: Unable to cast object of type 'System.String' to type 'System.Byte[]'.

嗨，只想問如何解決這一問題？我無法使用c＃在mysql中查看保存的查詢。我使用blob數據類型在mysql中保存圖像。而我是一名大學生，我們現在正在學校裏開展IT項目:)期待答案:) Godbless。 TIA。 ：d

這是我的代碼：

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows.Forms; 
using System.IO; 
using MySql.Data.MySqlClient; 


namespace WindowsFormsApplication1 
{ 
    public partial class Form2 : Form 
    { 
     public Form2() 
     { 
      InitializeComponent(); 
     } 


     private void button2_Click(object sender, EventArgs e) 
     { 

      string connStr = "server = 127.0.0.1; uid = root; " + "pwd =; database = dbSample"; 
      MySqlConnection con = new MySqlConnection(connStr); 
      MySqlCommand cmd; 
      MySqlDataAdapter da; 
      string query = "select * from image where name = '" + txtFirstname.Text + "' "; 
      cmd = new MySqlCommand(query, con); 
      da = new MySqlDataAdapter(); 
      DataTable dt = new DataTable(); 
      da.SelectCommand = cmd; 
      da.Fill(dt); 

      txtFirstname.Text = dt.Rows[0][0].ToString(); 
      byte[] ImageData = (byte[])dt.Rows[0][1];  // <----this is the error. 
      MemoryStream ms = new MemoryStream(ImageData); 
      pictureBox1.Image = Image.FromStream(ms); 

      da.Dispose(); 
     } 
    } 
} 

Answer 1

把右列

$字節[]的ImageData =（字節[]）dt.Rows [0] [1]） ;

Look 「無法將類型爲'System.String'的對象轉換爲鍵入'System.Byte []'」。

這意味着你選擇的列是字符串類型不能被轉換爲字節..