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！");                        }                                        }                                   }                        }        }    }}