[C#] How to select and check in SQL database?

[darkelfofdoom]

Well I'm having this problem, I'm having trouble with checking my login data with the database that is included. I can store data in it by registering, But I have no idea on how to check it when I want to login... Is there anyone that could help me out with this?

The code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace Tunestore
{
    public partial class Form1 : Form
    {

        //Variables
        string datum = DateTime.Now.Day + "/" + DateTime.Now.Month + "/" + DateTime.Now.Year;
        string version = " v" + DateTime.Now.Day + "-" + DateTime.Now.Month + "-" + DateTime.Now.Year + " Alpha 0.2";
        string sql = "SELECT * From tblUsers";
        string sqluser = "SELECT username From tblUsers Where username = tb.UserTl.Text";
        string sqlpass = "SELECT password From tblUsers Where password = tb.PassTl.Text";
        System.Data.SqlClient.SqlConnection con;
        System.Data.SqlClient.SqlDataAdapter da;
        System.Data.SqlClient.SqlCommandBuilder cb;
        DataSet ds1;
        DataRow dRow;
        int MaxRows = 0;
        int index = 0;
        
        public Form1()
        {
            InitializeComponent();
        }

        
        #region Event Handlers
        private void Form1_Load(object sender, EventArgs e) //Start Application
        {
            startFormMethod();
        }
        private void versionMenuItemTl_Click(object sender, EventArgs e) //Help > Version
        {
            versionMenuMethod();
        }
        private void aboutMenuItemTl_Click(object sender, EventArgs e) //Help > About
        {
            aboutMenuMethod();
        }
        private void btnLoginTl_Click(object sender, EventArgs e) //Login
        {
            loginMethod();
        }
        private void exitMenuItemTl_Click(object sender, EventArgs e) //File > Exit
        {
            Application.Exit();
        }
        private void openMenuItemTl_Click(object sender, EventArgs e) //File > Open
        {
            
        }
        private void saveMenuItemTl_Click(object sender, EventArgs e) //File > Save
        {
            
        }
        private void registerMenuItemTl_Click(object sender, EventArgs e) //Tools > Register
        {
            registeraddTabMethod();
        }
        private void btnRegisterTl_Click(object sender, EventArgs e)
        {
            registerMethod();
        }
        private void logoutMenuItemTl_Click(object sender, EventArgs e) //Tools > Logout
        {
            logoutMethod();
        }
        private void cbShowPassTl_CheckedChanged(object sender, EventArgs e) //Password Show|Hide
        {
            showpassMethod();
        }
        #endregion Event Handlers


        #region Methods
        private void startFormMethod() //Start Application
        {

            tabCtrlTl.TabPages.Remove(tabpageInvTl);
            tabCtrlTl.TabPages.Remove(tabpageRegTl);

            con = new System.Data.SqlClient.SqlConnection();
            ds1 = new DataSet();

            con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=C:\\Users\\Tim\\Documents\\My Dropbox\\VS2008\

\Users.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
           
            
            da = new System.Data.SqlClient.SqlDataAdapter(sql, con);
           
            con.Open();

            da.Fill(ds1, "Users");
            MaxRows = ds1.Tables["Users"].Rows.Count;

            con.Close();
            
            
            this.Text = "Deuntjes Winkel" + version;
        }
        private void showpassMethod() //Password Show|Hide
        {
            if (cbShowPassTl.Checked)
            {
                tbPassTl.UseSystemPasswordChar = false;
}
            else
            {
                tbPassTl.UseSystemPasswordChar = true;
            }
        }
        private void versionMenuMethod() //Help > Version
        {
           MessageBox.Show("Version: "+ version, 
                            "Version", 
                            MessageBoxButtons.OK, 
                            MessageBoxIcon.Information); 
        }
        private void aboutMenuMethod() //Help > About
        {
            MessageBox.Show("About" +
                            "\n\nName: \t\tTim Langen \nApplication: \tTune Store\nDate: \t\t" + datum +"\nSchool: \t\tROC ter AA, Helmond",
                            "About",
                            MessageBoxButtons.OK,
                            MessageBoxIcon.Information);
        }
        private void loginMethod() //Login
        {

            if (tbUserTl.Text == sqluser)
            {
                if (tbPassTl.Text == sqlpass)
                {
                    lblAccessTl.Text = "Access Granted!";
                    lblAccessTl.ForeColor = Color.Green;
                    MessageBox.Show("Login Granted", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    tabCtrlTl.TabPages.Add(tabpageInvTl);
                    tabCtrlTl.TabPages.Remove(tabpageModeTl);
                    tabCtrlTl.TabPages.Remove(tabpageRegTl);
                    logoutMenuItemTl.Visible = true;
                }
                else
                {
                    lblAccessTl.Text = "Access Denied!";
                    lblAccessTl.ForeColor = Color.Red;
                    MessageBox.Show("Password wrong, try again!", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }

            }
            else
            {
                lblAccessTl.Text = "Access Denied!";
                lblAccessTl.ForeColor = Color.Red;
                MessageBox.Show("Username wrong", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }

        }
        private void loginrequestMethod() //Login Database Aanvraag
        {
            DataRow dRow = ds1.Tables["Users"].Rows[index];

            tbUserTl.Text = dRow.ItemArray.GetValue(1).ToString();
            tbPassTl.Text = dRow.ItemArray.GetValue(2).ToString();
        }
        private void logoutMethod() //Logout
        {
            tbUserTl.Text = "";
            tbPassTl.Text = "";
            tabCtrlTl.TabPages.Add(tabpageModeTl);
            tabCtrlTl.TabPages.Remove(tabpageInvTl);
            logoutMenuItemTl.Visible = false;
            lblAccessTl.Text = "---";
            lblAccessTl.ForeColor = Color.Black;
            MessageBox.Show("Logged out successfully", "Logging out!", MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
        private void registeraddTabMethod() //Add Register Tabpage
        {
            tabCtrlTl.TabPages.Add(tabpageRegTl);
        }
        private void registerMethod() //Register
        {

            cb = new System.Data.SqlClient.SqlCommandBuilder(da);
            
            DataRow dRow = ds1.Tables["Users"].NewRow();

            dRow[1] = tbRegUsernameTl.Text;
            dRow[2] = tbRegPasswordTl.Text;

            ds1.Tables["Users"].Rows.Add(dRow);

            MaxRows = MaxRows + 1;
            index = MaxRows - 1;

            da.Update(ds1, "Users");
            
            MessageBox.Show("Thank you for registering", "Entry Added");

            tabCtrlTl.TabPages.Remove(tabpageRegTl);
        }
        #endregion


    }
}

The login method only :

        private void loginMethod() //Login
        {

            if (tbUserTl.Text == sqluser)
            {
                if (tbPassTl.Text == sqlpass)
                {
                    lblAccessTl.Text = "Access Granted!";
                    lblAccessTl.ForeColor = Color.Green;
                    MessageBox.Show("Login Granted", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    tabCtrlTl.TabPages.Add(tabpageInvTl);
                    tabCtrlTl.TabPages.Remove(tabpageModeTl);
                    tabCtrlTl.TabPages.Remove(tabpageRegTl);
                    logoutMenuItemTl.Visible = true;
                }
                else
                {
                    lblAccessTl.Text = "Access Denied!";
                    lblAccessTl.ForeColor = Color.Red;
                    MessageBox.Show("Password wrong, try again!", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }

            }
            else
            {
                lblAccessTl.Text = "Access Denied!";
                lblAccessTl.ForeColor = Color.Red;
                MessageBox.Show("Username wrong", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }

        }

 

[darkelfofdoom]

Problem is solved, topic may be removed.