string id = lblid.Text.Trim();
string info = FreeTextBox1.Text;
int xu = Convert.ToInt32(txtxu.Text);
string Title = txtTitle.Text.Trim();
string class1 = txtclass1.Text.Trim();
string class2 = txtclass2.Text.Trim();
string class3 = txtclass3.Text.Trim();
DateTime dt =Convert.ToDateTime(txtdt.Text);

string DataPatch = ConfigurationManager.AppSettings["data"];
string ConnetionString = "Provider=Microsoft.Jet.OLEDB.4.0;data source=" + HttpContext.Current.Server.MapPath(DataPatch);
Con = new OleDbConnection(ConnetionString);
cmd = new OleDbCommand("Update info set Title=@Title,xu=@xu,data=@dt,info=@info,class1=@class1,class2=@class2,class3=@class3 Where ID=@id", Con);
cmd.Parameters.Add(new OleDbParameter("@id", OleDbType.Char));
cmd.Parameters.Add(new OleDbParameter("@info", OleDbType.Char));
cmd.Parameters.Add(new OleDbParameter("@xu", OleDbType.Integer));
cmd.Parameters.Add(new OleDbParameter("@Title", OleDbType.Char));
cmd.Parameters.Add(new OleDbParameter("@class1", OleDbType.Char));
cmd.Parameters.Add(new OleDbParameter("@class2", OleDbType.Char));
cmd.Parameters.Add(new OleDbParameter("@class3", OleDbType.Char));
cmd.Parameters.Add(new OleDbParameter("@dt",OleDbType.Date));

cmd.Parameters["@id"].Value = id;
cmd.Parameters["@info"].Value = info;
cmd.Parameters["@xu"].Value = xu;
cmd.Parameters["@Title"].Value = Title;
cmd.Parameters["@class1"].Value = class1;
cmd.Parameters["@class2"].Value = class2;
cmd.Parameters["@class3"].Value = class3;
cmd.Parameters["@dt"].Value = dt;

Con.Open();
cmd.ExecuteNonQuery();
---------------------------------------------------------------------------------------
没有任何错误提示。可是就是修改不了数据？为什么？怎么解决啊