Zadanie2-4/Form1.cs

using MySql.Data.MySqlClient;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Kurs09
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            pass.PasswordChar = '*';
        }

        private void buttonLogin_Click(object sender, EventArgs e)
        {
            string loginUser = login.Text;
            String passUser = pass.Text;
            DB db = new DB();
            DataTable table = new DataTable();
            MySqlDataAdapter adapter = new MySqlDataAdapter();
            MySqlCommand command = new MySqlCommand("SELECT * FROM users WHERE login = @uL AND pass = @uP", db.GetConnection());
            command.Parameters.Add("@uL", MySqlDbType.VarChar).Value = loginUser;
            command.Parameters.Add("@uP", MySqlDbType.VarChar).Value = passUser;
            adapter.SelectCommand = command;
            adapter.Fill(table);
            if (table.Rows.Count > 0)
                MessageBox.Show("Yes");
            else
                MessageBox.Show("No");
        }
    }
}