飞来飞去简易教程-C#和Mysql数据库-实现用户登录

1.数据库建立如下：

2.操作流程如下：

（1）开始状态，数据库未连接

（2）链接数据库

（3）输入用户名和密码

（4）登陆成功

 

程序如下：

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 MysqlTest1
{
    public partial class Form1 : Form
    {
        MySqlConnection conn = null;//在类里面定义变量
        public Form1()
        {
            InitializeComponent();
                                    //在构造函数里面初始化
            conn = new MySqlConnection("Data Source=localhost;Initial Catalog=test;User ID=root;Password=mysql;");
                                    //在方法里面使用
        }

        private void btnLink_Click(object sender, EventArgs e)
        {
            conn.Open();        //打开对象
            if (conn.State.ToString() == "Open")
            {
                lab_state.Text  = "数据库连接成功！";
            }
            else
            {
                lab_state.Text = "数据库连接失败！";
            }

        }

        private void button1_Click(object sender, EventArgs e)
        {
            conn.Close();
            if(conn.State.ToString()=="Closed")
            {
                lab_state.Text = "数据库已关闭！";
            }
        }

        private void btn_load_Click(object sender, EventArgs e)
        {
            string userName=txt_User.Text.Trim();       //获取用户名
            string password = txt_Password.Text.Trim(); //获取密码
            string CmdStr = "Select * from test.user where name='"+userName+"' AND password='"+password+"'";
            MySqlCommand cmd = new MySqlCommand(CmdStr,conn);   //定义查询语句
           
            MySqlDataReader sreader = cmd.ExecuteReader();      //执行查询操作
            if (sreader.Read())
            {
                MessageBox.Show("登录成功！");
            }
            else
            {
                MessageBox.Show("登录失败！");
            }
            sreader.Close();        //每次执行完毕都得关闭reader
        }  
    }
}

 

补充：用户注册

（1）注册用户，输入用户名和密码

（2）点击注册，注册成功

（3）查看数据库-数据已插入成功

 

补充注册代码如下：

        private void btn_Sign_Click(object sender, EventArgs e)
        {
            string userName = txt_User.Text.Trim();         //获取文本信息，注意去掉多余空格
            string password = txt_Password.Text.Trim();

            string CmdStr = "INSERT INTO user VALUES('"+userName+"','"+password+"')";
            MySqlCommand cmd = new MySqlCommand(CmdStr,conn);
            int i = cmd.ExecuteNonQuery();
            if (i > 0)
            {
                MessageBox.Show("注册成功！");
            }

        }