private void btsign_Click(object sender, RoutedEventArgs e)

{

string usernum = UserNum.Text.ToString();

if (usernum.Length <= 0)

return;

string cmdtxt = "select User_Num from T_User where User_Num='" + usernum + "'";

DataTable table = new DataTable();

table = SqlHelper.ExecuteDataTable(cmdtxt);

if (table.Rows.Count <= 0)

MessageBox.Show("用户名不存在!");

else

{

if(remusername!=usernum)

{

Configuration cfa = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

cfa.AppSettings.Settings["usernum"].Value = usernum;

cfa.Save();

ConfigurationManager.RefreshSection("appSettings");

}

Online newwind = new Online(usernum);

newwind.Show();

this.Close();

}

}