C#登陆例子

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

namespace 登陆练习
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }



        private void incErrorTimes() {
            using (MySqlConnection conn = new MySqlConnection("Server=localhost;User Id=root;Password=xman;Persist Security Info=True;Database=test"))
            {
            conn.Open();
            using (MySqlCommand updataCmd = conn.CreateCommand())
                                {
                                    updataCmd.CommandText = "update user set errorTimes= errorTimes+1 where userName=@u";
                                    updataCmd.Parameters.Add(new MySqlParameter("u", userText.Text));
                                    updataCmd.ExecuteNonQuery();

                                }
        }
        }

        private void reSetErrorTimes()
        {
            using (MySqlConnection conn = new MySqlConnection("Server=localhost;User Id=root;Password=xman;Persist Security Info=True;Database=test"))
            {
                conn.Open();
                using (MySqlCommand updataCmd = conn.CreateCommand())
                {
                    updataCmd.CommandText = "update user set errorTimes= 0 where userName=@u";
                    updataCmd.Parameters.Add(new MySqlParameter("u", userText.Text));
                    updataCmd.ExecuteNonQuery();

                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            using (MySqlConnection conn = new MySqlConnection("Server=localhost;User Id=root;Password=xman;Persist Security Info=True;Database=test"))
            {
                conn.Open();
                using (MySqlCommand cmd = conn.CreateCommand()) {
                    cmd.CommandText = "select * from user where userName=@u ";
                    cmd.Parameters.Add(new MySqlParameter("u", userText.Text));
                    using (MySqlDataReader reader = cmd.ExecuteReader()) {

                        if (reader.Read())
                        {
                            int errorTimes = reader.GetInt32(reader.GetOrdinal("errorTimes"));
                            if (errorTimes > 3)
                            {

                                MessageBox.Show("登陆错误次数过多，禁止登陆！");
                                return;
                            }
                            String dbpassword = reader.GetString(reader.GetOrdinal("userPass"));
                            if (dbpassword == PassText.Text)
                            {
                                MessageBox.Show("登陆成功！");
                                reSetErrorTimes();
                            }
                            else
                            {
                                incErrorTimes();

                                MessageBox.Show("登陆失败！");
                            }

                            

                        }
                        else {
                            MessageBox.Show("用户不存在！");
                        }
                    
                    }
                   
                }
            
            }
        }
    }
}