我被这个问题搞得很蛋疼，大家过来看看该怎么改

Question

我在userinfo设置了role项，在界面上有RadioButton学生和RadioButton教师，点击学生按钮进入学生界面，点击教师按钮进入教师界面
现在我的问题是不管角色正确与否都会提示我用户角色错误
部分代码如下：
if (student.Checked == true)
        {
            
            string user = userName.Text;
            string pwd = passWord.Text;
            if (bc.validate(user))
            {
                Response.Write("<script>alert('用户名中不能含有非法字符');history.back()</script>");
                return;
            }
            if (bc.validate(pwd))
            {
                Response.Write("<script>alert('用户名中不能含有非法字符');history.back()</script>");
                return;
            }
            if (user == "")
            {
                Response.Write(bc.MessageBox("用户名不能为空！"));
            }
            if (pwd == "")
            {
                Response.Write(bc.MessageBox("密码不能为空！"));
            }
            SqlConnection con = new SqlConnection(ConfigurationManager.AppSettings["strcon"]);
            con.Open();
            SqlCommand scd = new SqlCommand("select count(*) from  userinfo where  name='" + user + "' and password='" + pwd + "'", con);
            int count = Convert.ToInt32(scd.ExecuteScalar());
            if (count > 0)
            {
                SqlCommand sd = new SqlCommand("select name,password,role from userinfo where name='" +user + "'", con);
                string name = Convert.ToString(sd.ExecuteScalar());
                string password = Convert.ToString(sd.ExecuteScalar());
                
                string role = Convert.ToString(sd.ExecuteScalar());
                Session["name"] = name.ToString();
                Session["password"] = password.ToString();
                Session["role"] = role.ToString();                if (role.ToString() == student.Text)
                {
                    Response.Redirect("student/Default.aspx", false);
                }
                else
                {
                    Response.Write("<script>alert('该用户名角色错误，请重新输入！');history.back()</script>");
                }
                con.Close();
            }
            else
            {
                Response.Write("<script>alert('该用户名不存在或密码错误或未参加教学活动，请重新输入！');history.back()</script>");
                return;
            }
        }

Answer 1

SqlCommand sd = new SqlCommand("select name,password,role from userinfo where name='" +user + "'", con); 
                string name = Convert.ToString(sd.ExecuteScalar()); 
                string password = Convert.ToString(sd.ExecuteScalar()); 
                
                string role = Convert.ToString(sd.ExecuteScalar()); 
                Session["name"] = name.ToString(); 
                Session["password"] = password.ToString(); 
                Session["role"] = role.ToString();                 if (role.ToString() == student.Text) 
                { 
                    Response.Redirect("student/Default.aspx", false); 
                } 
                else 
                { 
                    Response.Write(" <script>alert('该用户名角色错误，请重新输入！');history.back() </script>"); 
                } 
我估计是这错了。
SqlCommand sd = new SqlCommand("select name,password,role from userinfo where name='" +user + "'", con);
sd.ExecuteScalar()返回是什么？好像是执行查询，并返回第一行的第一列值。
你下面执行那么多次，当然会出错了。
方法：
SQLDateRead read =  sd.ExecuteRead();
if(read.HasRow)
{
   while(read.Read())
   {
                string name = read["name"].toString(); 
                string password = read["password"].toString();                
                string role = read["role"].toString();
                Session["name"] = name.ToString(); 
                Session["password"] = password.ToString(); 
                Session["role"] = role.ToString(); 
     然后再判断
    ............................   }
}

Answer 2

我晕，if (role.ToString() == student.Text) 在这句下断点，看看role.ToString()和student.Text分别是什么值？

Answer 3

role.ToString()和student.Text的值都是学生啊

Answer 4

SqlCommand sd = new SqlCommand("select name,password,role from userinfo where name='" +user + "'", con);
                string name = Convert.ToString(sd.ExecuteScalar());
                string password = Convert.ToString(sd.ExecuteScalar());
               
                string role = Convert.ToString(sd.ExecuteScalar()); 
有问题。 SqlCommand sd = new SqlCommand("select name,password,role from userinfo where name='" + user + "'", con);
        SqlDataAdapter myAdapter = new SqlDataAdapter(sd);
        DataSet mySet = new DataSet();
        myAdapter.Fill(mySet);
        DataRow userInfo = mySet.Tables[0].Rows[0];        string name = Convert.ToString(userInfo["name"]);
        string password = Convert.ToString(userInfo["password"]);
        string role = Convert.ToString(userInfo["role"]); 
这样试试。
上面用DataSet，下面用DataReader。效率嘛，楼主这么的需求DataReader高些string name = "";
        string password = "";
        string role = "";
        using (SqlConnection con = new SqlConnection(ConfigurationManager.AppSettings["strcon"]))
        {
            con.Open();
            SqlCommand sd = new SqlCommand("select name,password,role from userinfo where name='" + user + "'", con);
            using (SqlDataReader reader = sd.ExecuteReader(CommandBehavior.CloseConnection))
            {
                if (reader.Read())
                {
                    name = Convert.ToString(reader["name"]);
                    password = Convert.ToString(reader["password"]);
                    role = Convert.ToString(reader["role"]);
                    Session["name"] = name;
                    Session["password"] = password;
                    Session["role"] = role;
                }
                else // 记录不存在
                {
                    Response.Write(" <script>alert('该用户名不存在或密码错误或未参加教学活动，请重新输入！');history.back() </script>");  
                }
            }
            if (role == student.Text)
            {
                Response.Redirect("student/Default.aspx", false); 
            }
            else
            {
                Response.Write(" <script>alert('该用户名角色错误，请重新输入！');history.back() </script>"); 
            }