请问这一句：userName = request.getParameter("userName" + userId);

request.getParameter("username") == null "" :request.getPara if (Session["UserName"] == null || Session["UserName"].ToStr com.Parameters.AddWithValue("@userName",userName); S_USERNAME=:USERNAME AND S_PASSWORD=:PASSWORD"; 关于Trim（）string UserName = txtUserName.Text;和string UserName request.getparameter("name") Select a username是什么意思 please check username是什么意思 Username unavailable 意思 Choose Username是什么意思 this username is available! Username 什么意思?