System.FormatException: 输入字符串的格式不正确。
NewsService newsService = new NewsService();
  protected void Page_Load(object sender, EventArgs e)
  {
  ddlNewsType.DataSource = newsService.Get_D_NewsType();
  ddlNewsType.DataValueField = "ClsID";
  ddlNewsType.DataTextField = "ClsName";
  ddlNewsType.DataBind();
   
  ddlNewsType.Items.Insert(0, " --请选择分类--");
  }
  protected void btnSubmit_Click(object sender, EventArgs e)
  {
  string newsTitle = txtNewsName.Text.Trim();
  string newsType = ddlNewsType.SelectedItem.Text;
  string newsFrom = txtNewsSource.Text.Trim();
  int ClsID = Convert.ToInt32(ddlNewsType.SelectedValue);
  string newsContent = CKEditorControl1.Text;
  DateTime time = DateTime.Now;
  if (newsService.Add_T_News(ClsID,newsTitle,newsContent,time,newsFrom))
  {
  Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", "<script>alert('添加成功')</script>");
  }
  else
  {
  Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", "<script>alert('添加失败')</script>");
  }
  }

上面是错误出现的地方 就这里int ClsID = Convert.ToInt32(ddlNewsType.SelectedValue);



下面是访问数据库
 /// <summary>
  /// 想新闻表中添加新闻
  /// </summary>
  /// <param name="ClsID">新闻类别ID</param>
  /// <param name="InfoName">新闻名称</param>
  /// <param name="InfoNote">新闻内容</param>
  /// <param name="InfoDate">添加新闻的时间</param>
  /// <param name="writefrom">新闻来源</param>
  /// <returns></returns>
  public bool Add_T_News(int ClsID, string InfoName, string InfoNote, DateTime InfoDate, string writefrom)
  {
  try
  {
  string sqlStr = "insert into T_News(ClsID,InfoName,InfoNote,InfoDate,writefrom) values(" + ClsID + ",'" + InfoName + "','" + InfoNote + "'," + InfoDate + ",'" + writefrom + "')";
  OleDbCommand cmd = new OleDbCommand(sqlStr, con);
   
  con.Open();
  if (cmd.ExecuteNonQuery() > 0)
  {
  return true;
  }
  return false;

  }
  catch (Exception e)
  {

  throw e;
  }
  finally
  {
  con.Close();
  }
  }

连接的是ACCESS数据库

------解决方案--------------------

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是的~