Login using different user in a different page?

I have this code here for logging in:

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)
        {
            Student();
            Teacher();
        }
        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);

            for (; ; )
            {
                try
                {
                    //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();

                    if (username == "admin" && pass == "cmpe1234")
                    {
                        Session["adminlogin"] = username;
                        Response.Redirect("AdministratorPage.aspx");
                    }
                    else 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>");
                    break;
                }
            }
        }

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

            //String decleration
            string teacherusername = (this.UserName.Value);
            string password = (this.Password.Value);

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

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

            for(;;)
            {
                try
                {
                    //string decleration and getting each rows of the Student database
                    string teacherid = teacherData.Tables[0].Rows[teachercounter]["TeacherID"].ToString();
                    string teacherpassword = teacherData.Tables[0].Rows[teachercounter]["Password"].ToString();
                    string teacherfirstname = teacherData.Tables[0].Rows[teachercounter]["FirstName"].ToString();
                    string teacherlastname = teacherData.Tables[0].Rows[teachercounter]["LastName"].ToString();
                    string department = teacherData.Tables[0].Rows[teachercounter]["Department"].ToString();
                    string position = teacherData.Tables[0].Rows[teachercounter]["Position"].ToString();

                    if (teacherusername == "admin" && password == "cmpe1234")
                    {
                        Session["adminlogin"] = teacherusername;
                        Response.Redirect("AdministratorPage.aspx");
                    }
                    else if (teacherusername == teacherid && password == teacherpassword)
                    {
                        //For Student Data Sessions
                        Session["teacherlogin"] = teacherid;
                        Session["teacherfirstname"] = teacherfirstname;
                        Session["teacherlastname"] = teacherlastname;
                        Session["department"] = department;
                        Session["position"] = position;

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

                        break;
                    }
                    else
                    {
                        teachercounter++;
                    }
                }
                catch
                {
                    break;
                }
            }
        }
    }
}

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?

    protected void Button1_Click(object sender, EventArgs e)
    {
        Student();
        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.