在其他页面中使用其他用户登录？

Question

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using MSSQLConnector;
using System.Data;

namespace SoftwareAnalysisAndDesign.SAD
{
    public partial class OnlineAppSyss : System.Web.UI.Page
    {
        private MSConnector connector = new MSConnector();
        //string queries for each DataSet
        string query = null;
        string teacherquery = null;
        string subjectquery = null;
        string schoolfeequery = null;
        string accountdetailsquery = null;
        int rowcounter = 0;
        int teachercounter = 0;

        //DataSet and DataTable initialization
        private DataSet studentData;
        private DataSet subjectData;
        private DataSet schoolfeeData;
        private DataSet teacherData;
        private DataSet accountdetailsData;
        private DataTable subjectTable;
        private DataTable schoolfeeTable;
        private DataTable accountdetailsTable;
        protected void Page_Load(object sender, EventArgs e)
        {
        }
        protected void Button1_Click(object sender, EventArgs e)
        {
            if (dropdownrole.SelectedItem.Value == "Admin")
            {
                Admin();
            }
            else if (dropdownrole.SelectedItem.Value == "Student")
            {
                Student();
            }
            else if (dropdownrole.SelectedItem.Value == "Teacher")
            {
                Teacher();
            }
        }
        public void Admin()
        {
            //String decleration
            string adminusername = (this.UserName.Value);
            string adminpass = (this.Password.Value);

            try
            {
                if (adminusername == "admin" && adminpass == "cmpe1234")
                {
                    Session["adminlogin"] = adminusername;
                    Response.Redirect("AdministratorPage.aspx");
                }
            }
            catch
            {
                Response.Write("<script language=javascript>alert('Username and password does not match. Try again');</script>");
            }
        }
        public void Student()
        {
            //Connection String
            connector.ConnectionString = "Data Source=keith;Initial Catalog=SAD;Integrated Security=True";

            //String decleration
            string username = (this.UserName.Value);
            string pass = (this.Password.Value);

            //query database from sql server management studio for student
            query = "select studentid,password,firstname,lastname,course,year from student";

            //execute query for student
            studentData = connector.ExecuteQuery(query);


            try
            {
                for (; ; )
                {
                    //string decleration and getting each rows of the Student database
                    string userid = studentData.Tables[0].Rows[rowcounter]["StudentID"].ToString();
                    string password = studentData.Tables[0].Rows[rowcounter]["Password"].ToString();
                    string firstname = studentData.Tables[0].Rows[rowcounter]["FirstName"].ToString();
                    string lastname = studentData.Tables[0].Rows[rowcounter]["LastName"].ToString();
                    string course = studentData.Tables[0].Rows[rowcounter]["Course"].ToString();
                    string year = studentData.Tables[0].Rows[rowcounter]["Year"].ToString();


                    //For Student Condition
                    if (username == userid && pass == password)
                    {
                        //For Student Data Sessions
                        Session["login"] = userid;
                        Session["firstname"] = firstname;
                        Session["lastname"] = lastname;
                        Session["course"] = course;
                        Session["year"] = year;

                        //For Account Details Data
                        accountdetailsquery = "select StudentID,FirstName,MiddleName,LastName,Age,Province,City,Course,Year,College,Department,ContactNumber,Email from student where studentid = " + username + "";

                        //query database from sql server management studio for student as accountDetails Information
                        accountdetailsData = connector.ExecuteQuery(accountdetailsquery);

                        accountdetailsTable = accountdetailsData.Tables[0];
                        Session["AccountDetails"] = accountdetailsTable;

                        //For SchoolFee Data
                        //query database from sql server management studio for schoolfee
                        schoolfeequery = "select DatePaid,AmountPaid,CurrentBalance,TotalBalance,Semester from schoolfee where studentid = " + username + "";

                        //execute query for schoolfee
                        schoolfeeData = connector.ExecuteQuery(schoolfeequery);

                        //get all data rows for SchoolFee and store it into DataTable
                        schoolfeeTable = schoolfeeData.Tables[0];
                        Session["SchoolFee"] = schoolfeeTable;

                        //For Subject Data
                        //query database from sql server management studio for subject
                        subjectquery = "select CourseNo,CourseDescription,Units,Day,StartTime,EndTime,Room from subject where studentid = " + username + "";

                        //execute query for subject
                        subjectData = connector.ExecuteQuery(subjectquery);

                        //get all data rows for Subject and store it into DataTable 
                        subjectTable = subjectData.Tables[0];
                        Session["Subjects"] = subjectTable;

                        //Redirect the page to Student Page after the user successfully logs in.
                        Response.Redirect("StudentPage.aspx", true);

                        break;
                    }
                    else
                    {
                        rowcounter++;
                    }
                }

            }
            catch
            {
                Response.Write("<script language=javascript>alert('Username and password does not match. Try again');</script>");
            }

        }
        public void Teacher()
        {
            //Connection String
            connector.ConnectionString = "Data Source=keith;Initial Catalog=SAD;Integrated Security=True";

            //String decleration
            string username = (this.UserName.Value);
            string pass = (this.Password.Value);

            //query database from sql server management studio for student
            teacherquery = "select teacherid,password,firstname,lastname,department,position from teacher";

            //execute query for student
            teacherData = connector.ExecuteQuery(teacherquery);

            try
            {
                for (; ; )
                {
                    //string decleration and getting each rows of the Teacher database
                    string teacheruserid = teacherData.Tables[0].Rows[rowcounter]["TeacherID"].ToString();
                    string teacherpassword = teacherData.Tables[0].Rows[rowcounter]["Password"].ToString();
                    string teacherfirstname = teacherData.Tables[0].Rows[rowcounter]["FirstName"].ToString();
                    string teacherlastname = teacherData.Tables[0].Rows[rowcounter]["LastName"].ToString();
                    string teacherdepartment = teacherData.Tables[0].Rows[rowcounter]["Department"].ToString();
                    string teacherposition = teacherData.Tables[0].Rows[rowcounter]["Position"].ToString();

                    //For Teacher Condition
                    if (username == teacheruserid && pass == teacherpassword)
                    {
                        Session["teacherlogin"] = teacheruserid;
                        Session["teacherfirstname"] = teacherfirstname;
                        Session["teacherlastname"] = teacherlastname;
                        Session["department"] = teacherdepartment;
                        Session["position"] = teacherposition;

                        //Redirect the page to Student Page after the user successfully logs in.
                        Response.Redirect("TeacherPage.aspx", true);
                        break;
                    }
                    else
                    {
                        rowcounter++;
                    }
                }
            }
            catch
            {
                Response.Write("<script language=javascript>alert('Username and password does not match. Try again (teacher)');</script>");
            }
        }
    }
}

My problem is I can't access the teacher page in this code, it will only access the student page. What Condition should I use in my system to avoid redundancy?

This is my aspx Code for dropdownlist:

<asp:DropDownList runat="server" id="dropdownrole">
    <asp:ListItem Text="Admin">Admin</asp:ListItem>
    <asp:ListItem Text="Student">Student</asp:ListItem>
    <asp:ListItem Text="Teacher">Teacher</asp:ListItem>
</asp:DropDownList>

and the login button:

 protected void Button1_Click(object sender, EventArgs e)
        {
            if (dropdownrole.SelectedItem.Value == "Admin")
            {
                Admin();
            }
            else if (dropdownrole.SelectedItem.Value == "Student")
            {
                Student();
            }
            else if (dropdownrole.SelectedItem.Value == "Teacher")
            {
                Teacher();
            }
        }

I want to have a condition that If a username and password input detects either of the 2 users, it will redirect to their specific webpage. Please Help.

Answer 1

You didn't select teacher password in your teacherquery therefor the teacherpassword is always null that why the condition password == teacherpassword is always false.

Like DPac pointed out, you don't need to query all of rows just to verify the username & password, just select username & password only first, if it is correct then select all of rows you want and assign them to sessions, then redirect.

About the problem if student's username is as same as teacher's username, there will be whole lot of troubles, to avoid it (without doing whole lot of thing) is to add 1 more int row in both tables named userRole (ex: 1 = admin, 2 = teacher, 3 = student etc.) and allow it to be null. After that go in each table and update that row to proper value (for example in student table: UPDATE student SET userRole = 3 ). After update all of row then go to Design and set the userRole to not allow null Now the username + userRole combination (should have been your primary key) will make your life much easier.

Answer 2

Although i would prefer @ronaldinho's way of giving a RoleId column to both tables.Here is what you can do without disturbing the database.

Just add a dropdownlist with items "Teacher" and "Student" on your login page.So when some one tries to log in they have to select their role and then enter. This way you can direct the code as

   protected void Button1_Click(object sender, EventArgs e)
    {
        if (dropdownrole.SelectedItem.Text == "Admin")
        {
            Admin();
        }
        else if (dropdownrole.SelectedItem.Text == "Student")
        {
            Student();
        }
        else if (dropdownrole.SelectedItem.Text == "Teacher")
        {
            Teacher();
        }
    }

See if it is possible for you