我是編程新手（在大學學習的第一年），我正在開發一個小型應用程序。我有一個窗口，用戶可以在其中從 SQL 檢索數據，DataGrid以及Button將一些數據從DataGrid數據導出到文本文件。這是我用來從 SQL 獲取數據的代碼：SqlConnection con = new SqlConnection("Server = localhost;Database = autoser; Integrated Security = true");SqlCommand cmd = new SqlCommand("selectproduct", con); // Using a Store Procedure.cmd.CommandType = CommandType.StoredProcedure;DataTable dt = new DataTable("dtList");cmd.Parameters.AddWithValue("@Code", txtbarcode.Text);SqlDataAdapter da = new SqlDataAdapter(cmd);da.Fill(dt);data.ItemsSource = dt.DefaultView;SqlDataAdapter adapt = new SqlDataAdapter(cmd);DataSet ds = new DataSet();adapt.Fill(ds);con.Close();int count = ds.Tables[0].Rows.Count;if (count == 0){    MessageBox.Show("This product doesn't excist");    SystemSounds.Hand.Play();}else if (count == 1){    lblinfo.Visibility = Visibility.Visible;    SystemSounds.Asterisk.Play();}這是我用來編寫文本文件的代碼：{    using (StreamWriter writer = new StreamWriter("D:\\test.txt", true))    {        writer.WriteLine("Welcome");        writer.WriteLine("E N T E R N E T");    }    using (StreamWriter writer = new StreamWriter("D:\\test.txt", true))    {        writer.WriteLine(data.Items);    }    using (StreamWriter writer = new StreamWriter("D:\\test.txt", true))    {        writer.WriteLine(data.Items);    }    // Append line to the file.    using (StreamWriter writer = new StreamWriter("D:\\test.txt", true))    {        writer.WriteLine("---------------------------------------");        writer.WriteLine("             Thank You!   ");        writer.WriteLine("        " + DateTime.Now + "              ");    }}當我打開文本文件時，我得到了這些數據WelcomeE N T E R N E TSystem.Windows.Controls.ItemCollection -   Why isn't show the data grid data---------------------------------------    Thank You       7/26/2018 12:38:37 PM   我的問題是：我的錯誤在哪里導致數據DataGrid無法以正確的方式顯示？