运行效果

MySQL数据库的使用

官网下载安装即可，安装的时候选择这两个

安装完打开是这样

使用方式

这样可以查看表中列的属性

可以在表中直接修改数据，点击apply，自动生成sql语句。

一些sql笔记

cd C:\Program Files\MySQL\MySQL Server 8.0\bin
show global variables like "%datadir%";
mysql –uroot –p111111

#插入数据
INSERT INTO `customer`(`CNAME`, `CAGE`, `CSEX`, `CID`, `CPHONE`, `CPASSWORD`, `CEMAIL`)
VALUES
("ceshi1", '3', '女', '100001', '100002', '100002', '100000');#可以单引号，也可以双引号

#插入数据
INSERT INTO `itravelin`.`customer` (`CNAME`, `CAGE`, `CSEX`, `CID`, `CPHONE`, `CPASSWORD`, `CEMAIL`) 
VALUES
('ceshi1', '3', '女', '100000', '100000', '100000', '100000');

#查找
SELECT CNAME FROM itravelin.customer;#指定要查找的内容
SELECT * FROM itravelin.customer;#星号显示所有列
SELECT * FROM itravelin.customer where CSEX="女";

#添加列：在一个已经建好的表中添加一列，这一列在表的最后一列位置
alter table `itravelin`.`customer` add column BANANCE varchar(20) not null;
alter table `itravelin`.`customer` add column STOCK0 varchar(20) not null;
alter table `itravelin`.`customer` add column STOCK1 varchar(20) not null;
alter table `itravelin`.`customer` add column STOCK2 varchar(20) not null;
alter table `itravelin`.`customer` add column STOCK3 varchar(20) not null;
alter table `itravelin`.`customer` add column STOCK4 varchar(20) not null;

#添加列：在一个已经建好的表中添加一列，这一列在表的指定列之后
alter table `itravelin`.`customer` add column BANANCE_BF varchar(20) not null after `CEMAIL`;

#修改列名
alter table `itravelin`.`customer` change BANANCE BALANCE varchar(20);
alter table `itravelin`.`customer` change BALANCE_BF TOTALVALUE varchar(20);

CHAR_LENGTH

DELETE FROM `itravelin`.`customer` WHERE (length(`CPHONE`)<11);

select * from `itravelin`.`customer`  where length(`CPHONE`)<11;

#按照条件，修改表中数据
UPDATE `itravelin`.`customer` SET `BALANCE`  = '1000000' WHERE (`BALANCE` != "1000000");
UPDATE `itravelin`.`customer` SET `STOCK0`  = '0' WHERE (`STOCK0`  != '0' );
UPDATE `itravelin`.`customer` SET `STOCK1`  = '0' WHERE (`STOCK1`  != '0' );
UPDATE `itravelin`.`customer` SET `STOCK2`  = '0' WHERE (`STOCK2`  != '0' );
UPDATE `itravelin`.`customer` SET `STOCK3`  = '0' WHERE (`STOCK3`  != '0' );
UPDATE `itravelin`.`customer` SET `STOCK4`  = '0' WHERE (`STOCK4`  != '0' );

#创建一个表
CREATE TABLE IF NOT EXISTS STOCK(CNAME varchar(20) not null,PRICE varchar(20) not null,PRIMARY key(PRICE))engine = InnoDB default CHARSET=utf8;

#修改数据
UPDATE `itravelin`.`stock` SET `PRICE` = '16' WHERE (`PRICE` = '14');


#移动列
alter table customer modify STOCK4 varchar(20) after STOCK3;

另外，关于为什么需要添加环境变量：

1、计算机在执行命令的时候是在环境变量找对应的命令的位置的。如果不正确设置环境变量就不能正确使用相应的命令
2、比如说你要执行 java 命令，你不设置环境变量path包括你的jdk安装路径，那系统去哪找你的java.exe文件。
如果执行某个命令，系统无法在当前文件夹里找到对应的.exe，那么系统就会去path包含的路径找挨个找看是否能知道对应的.exe，一旦找到第一个对应的.exe就运行命令，其他的路径下就不找了。如果找不到你就会看到“系统找不到某某命令”的提示。
其他的环境变量也一样的用途，只不过是用来存储一些信息用的，这些信息可以被系统使用，也可以被你的应用程序使用

在C#中要添加如下引用：

主要窗体及代码

login

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 traveling
{
    public partial class login : Form
    {
        public static string PHONENUM;

        //update info
        public void updateData(string phonenum)
        {
            int totalValue;     //your stock worth + money left
            int balance;       //money left
            double profitRate;
            int[] holdBounds = new int[5];

            textBox1.Text = phonenum;

            try
            {
                //create database connection
                string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                MySqlConnection con = new MySqlConnection(strcon);

                //open database
                con.Open();

                //sql
                string sql = "select TOTALVALUE from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                MySqlCommand cmd = new MySqlCommand(sql, con);
                totalValue = Convert.ToInt32(cmd.ExecuteScalar());
                textBox2.Text = Convert.ToString(totalValue);

                sql = "select BALANCE from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                cmd = new MySqlCommand(sql, con);
                balance = Convert.ToInt32(cmd.ExecuteScalar());
                textBox3.Text = Convert.ToString(balance);

                profitRate = ((double)totalValue - 1000000) / 1000000;
                textBox4.Text = Convert.ToString(profitRate);

                for (int i = 0; i < 5; i++)
                {
                    sql = "select STOCK" + i + " from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                    cmd = new MySqlCommand(sql, con);
                    holdBounds[i] = Convert.ToInt32(cmd.ExecuteScalar());
                }
                textBox5.Text = Convert.ToString(holdBounds[0]);
                textBox6.Text = Convert.ToString(holdBounds[1]);
                textBox7.Text = Convert.ToString(holdBounds[2]);
                textBox8.Text = Convert.ToString(holdBounds[3]);
                textBox9.Text = Convert.ToString(holdBounds[4]);

                Application.DoEvents();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex + "发生异常");
                throw;
            }
        }

        public login()
        {
            InitializeComponent();
        }

        //log in
        private void btnlogin_Click(object sender, EventArgs e)
        {
            //get input
            string userName = this.usernametxt.Text;
            string userPassword = this.passwordtxt.Text;

            //input legal
            if (FunctionDefine.Isempty(userName))
            {
                MessageBox.Show("用户名不能为空！");
                return;
            }
            if (FunctionDefine.Isempty(userPassword))
            {
                MessageBox.Show("密码不能为空！");
            }

            //traveller login
            if (this.radiocustomer.Checked)
            {
                Customer customer = new Customer(userPassword);
                customer.Setcphone(userName);
                customer.Setcpassword(userPassword);

                try
                {
                    //connect
                    string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                    MySqlConnection con = new MySqlConnection(strcon);
                    //open
                    con.Open();
                    //sql
                    string sql = "select count(*) from itravelin.customer where CPHONE = '" + userName + "' and cpassword = '" + userPassword + "'";
                    MySqlCommand com = new MySqlCommand(sql, con);
                    //check psw
                    if (Convert.ToInt32(com.ExecuteScalar()) > 0)
                    {
                        MessageBox.Show("登录成功！");

                        //update info
                        label15.ForeColor = Color.LimeGreen;
                        label15.Text = "状态：已登录";
                        updateData(userName);
                        Application.DoEvents();

                        //new winform
                        //Main_customer main_customer = new Main_customer();

                        //this.DialogResult = DialogResult.OK;
                        //main_customer.ShowDialog();
                        //this.Dispose();
                        //this.Close();
                        //Close();
                    }

                    //phonenum or password wrong
                    else
                    {
                        MessageBox.Show("用户名或密码错误！");
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message.ToString() + "打开数据库失败");
                }
            }


            //admin login
            else if (this.radioadmin.Checked)
            {
                Administrator administrator = new Administrator(userPassword);
                administrator.Setusername(userName);
                administrator.Setpassword(userPassword);

                try
                {
                    //connect
                    string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                    MySqlConnection con = new MySqlConnection(strcon);
                    //open
                    con.Open();
                    //sql
                    string sql = "select count(*) from itravelin.manager where username = '" + userName + "' and password = '" + userPassword + "'";
                    MySqlCommand com = new MySqlCommand(sql, con);
                    //check psw
                    if (Convert.ToInt32(com.ExecuteScalar()) > 0)
                    {
                        MessageBox.Show("登录成功！");
                        //new winform
                        Main_administrator main_administrator = new Main_administrator();
                        //this.DialogResult = DialogResult.OK;
                        main_administrator.ShowDialog();
                        //this.Dispose();
                        //this.Close();

                    }

                    //phonenum or password wrong
                    else
                    {
                        MessageBox.Show("用户名或密码错误！");
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message.ToString() + "异常");
                }
            }

            else MessageBox.Show("请选择您的登录方式！");
        }

        private void btnregister_Click(object sender, EventArgs e)
        {
            register selectregister = new register();
            selectregister.Show();
        }





        //startSimulation
        private void button1_Click(object sender, EventArgs e)
        {
            if (label15.Text == "状态：未登录")
            {
                MessageBox.Show("请先登录！");
                return;
            }
            startSimulation mysimulation = new startSimulation();
            PHONENUM = textBox1.Text;

            mysimulation.ShowDialog();

            button3_Click(null, null);
        }

        //save and close
        private void button2_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        //button_update data
        private void button3_Click(object sender, EventArgs e)
        {
            string phonenum = textBox1.Text;
            int totalValue;     //your stock worth + money left
            int balance;       //money left
            double profitRate;
            int[] holdBounds = new int[5];

            try
            {
                //create database connection
                string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                MySqlConnection con = new MySqlConnection(strcon);

                //open database
                con.Open();

                //sql
                string sql = "select TOTALVALUE from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                MySqlCommand cmd = new MySqlCommand(sql, con);
                totalValue = Convert.ToInt32(cmd.ExecuteScalar());
                textBox2.Text = Convert.ToString(totalValue);

                sql = "select BALANCE from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                cmd = new MySqlCommand(sql, con);
                balance = Convert.ToInt32(cmd.ExecuteScalar());
                textBox3.Text = Convert.ToString(balance);

                profitRate = ((double)totalValue - 1000000) / 1000000;
                textBox4.Text = Convert.ToString(profitRate);

                for (int i = 0; i < 5; i++)
                {
                    sql = "select STOCK" + i + " from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                    cmd = new MySqlCommand(sql, con);
                    holdBounds[i] = Convert.ToInt32(cmd.ExecuteScalar());
                }
                textBox5.Text = Convert.ToString(holdBounds[0]);
                textBox6.Text = Convert.ToString(holdBounds[1]);
                textBox7.Text = Convert.ToString(holdBounds[2]);
                textBox8.Text = Convert.ToString(holdBounds[3]);
                textBox9.Text = Convert.ToString(holdBounds[4]);

                Application.DoEvents();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex + "发生异常");
                throw;
            }
        }
    }
}

startSimulation

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;
using MySql.Data.MySqlClient;
using System.Threading;

namespace traveling
{
    public partial class startSimulation : Form
    {
        //update info
        public void updateData()
        {
            string phonenum = login.PHONENUM;

            int totalValue;     //your stock worth + money left
            int balance;       //money left
            int[] holdBounds = new int[5];

            try
            {
                //create database connection
                string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                MySqlConnection con = new MySqlConnection(strcon);

                //open database
                con.Open();

                //sql
                string sql = "select TOTALVALUE from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                MySqlCommand cmd = new MySqlCommand(sql, con);
                totalValue = Convert.ToInt32(cmd.ExecuteScalar());
                textBox29.Text = Convert.ToString(totalValue);

                sql = "select BALANCE from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                cmd = new MySqlCommand(sql, con);
                balance = Convert.ToInt32(cmd.ExecuteScalar());
                textBox30.Text = Convert.ToString(balance);

                for (int i = 0; i < 5; i++)
                {
                    sql = "select STOCK" + i + " from itravelin.customer where CPHONE=\"" + phonenum + "\";";
                    cmd = new MySqlCommand(sql, con);
                    holdBounds[i] = Convert.ToInt32(cmd.ExecuteScalar());
                }
                tbstock0.Text = Convert.ToString(holdBounds[0]);
                tbstock1.Text = Convert.ToString(holdBounds[1]);
                tbstock2.Text = Convert.ToString(holdBounds[2]);
                tbstock3.Text = Convert.ToString(holdBounds[3]);
                tbstock4.Text = Convert.ToString(holdBounds[4]);

                Application.DoEvents();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex + "发生异常");
                throw;
            }
        }
        public startSimulation()
        {
            InitializeComponent();
        }

        //start simulation
        private void button5_Click(object sender, EventArgs e)
        {
            //initialize price from database read
            int[] priceStock = new int[5];
            for (int i = 0; i < 5; i++)
            {
                try
                {
                    //create database connection
                    string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                    MySqlConnection con = new MySqlConnection(strcon);

                    //open database
                    con.Open();

                    //sql
                    string sql = "select PRICE from itravelin.stock where CNAME=\"stock" + i + "\";";
                    MySqlCommand cmd = new MySqlCommand(sql, con);

                    //get result
                    //MySqlDataReader reader = cmd.ExecuteReader();
                    //reader.Close();//close then open

                    priceStock[i] = Convert.ToInt32(cmd.ExecuteScalar());
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex + "发生异常");
                    throw;
                }
            }
            //show price in textbox
            textBox1.Text = priceStock[0].ToString();
            textBox2.Text = priceStock[1].ToString();
            textBox3.Text = priceStock[2].ToString();
            textBox4.Text = priceStock[3].ToString();
            textBox5.Text = priceStock[4].ToString();

            //1
            textBox18.Text = textBox1.Text;
            textBox23.Text = textBox1.Text;

            //2
            textBox17.Text = textBox2.Text;
            textBox22.Text = textBox2.Text;

            //3
            textBox16.Text = textBox3.Text;
            textBox21.Text = textBox3.Text;

            //4
            textBox15.Text = textBox4.Text;
            textBox20.Text = textBox4.Text;

            //5
            textBox14.Text = textBox5.Text;
            textBox19.Text = textBox5.Text;

            Application.DoEvents();

            //timer
            System.Timers.Timer timer = new System.Timers.Timer();
            timer.Interval = 1000;

            timer.Start();
            timer.Elapsed += new System.Timers.ElapsedEventHandler(mytimer);

            updateData();
        }



        private void mytimer(object sender, EventArgs e)
        {
            //get price from textbox
            int[] priceStock = new int[5];
            priceStock[0] = int.Parse(textBox1.Text);
            priceStock[1] = int.Parse(textBox2.Text);
            priceStock[2] = int.Parse(textBox3.Text);
            priceStock[3] = int.Parse(textBox4.Text);
            priceStock[4] = int.Parse(textBox5.Text);

            //random
            Random rd = new Random();

            //wait 1 sec
            Application.DoEvents();

            for (int i = 0; i < 5; i++)
            {
                if (priceStock[i] > 200) priceStock[i] += rd.Next(-10, 4);//avoid price too high
                else priceStock[i] += rd.Next(-3, 4);

                if (priceStock[i] < 1) priceStock[i] = 1;

            }
            this.Invoke(new Action(() =>
            {
                textBox1.Text = priceStock[0].ToString();
                textBox2.Text = priceStock[1].ToString();
                textBox3.Text = priceStock[2].ToString();
                textBox4.Text = priceStock[3].ToString();
                textBox5.Text = priceStock[4].ToString();

                textBox29.Text = Convert.ToString(int.Parse(textBox30.Text)+priceStock[0] * int.Parse(tbstock0.Text) + priceStock[1] * int.Parse(tbstock1.Text) + priceStock[2] * int.Parse(tbstock2.Text) + priceStock[3] * int.Parse(tbstock3.Text) + priceStock[4] * int.Parse(tbstock4.Text));
                //find max
                //1
                if (int.Parse(textBox1.Text) > int.Parse(textBox18.Text)) textBox18.Text = textBox1.Text;
                if (int.Parse(textBox1.Text) < int.Parse(textBox23.Text)) textBox23.Text = textBox1.Text;

                //2
                if (int.Parse(textBox2.Text) > int.Parse(textBox17.Text)) textBox17.Text = textBox2.Text;
                if (int.Parse(textBox2.Text) < int.Parse(textBox22.Text)) textBox22.Text = textBox2.Text;

                //3
                if (int.Parse(textBox3.Text) > int.Parse(textBox16.Text)) textBox16.Text = textBox3.Text;
                if (int.Parse(textBox3.Text) < int.Parse(textBox21.Text)) textBox21.Text = textBox3.Text;

                //4
                if (int.Parse(textBox4.Text) > int.Parse(textBox15.Text)) textBox15.Text = textBox4.Text;
                if (int.Parse(textBox4.Text) < int.Parse(textBox20.Text)) textBox20.Text = textBox4.Text;

                //5
                if (int.Parse(textBox5.Text) > int.Parse(textBox14.Text)) textBox14.Text = textBox5.Text;
                if (int.Parse(textBox5.Text) < int.Parse(textBox19.Text)) textBox19.Text = textBox5.Text;
                Application.DoEvents();

                //check trade
                if (WANTBUY == true)
                {
                    //if can buy
                    if (priceStock[STOCKBUYNUM] <= BUYPRICE)
                    {
                        //update data
                        switch (STOCKBUYNUM)
                        {
                            case 0: tbstock0.Text = Convert.ToString(int.Parse(tbstock0.Text) + BUYNUM); logger.Text += "交易成功,股票序号0,成交价格："; logger.Text += Convert.ToString(BUYPRICE); logger.Text += "\r\n"; break;
                            case 1: tbstock1.Text = Convert.ToString(int.Parse(tbstock1.Text) + BUYNUM); logger.Text += "交易成功,股票序号1,成交价格："; logger.Text += Convert.ToString(BUYPRICE); logger.Text += "\r\n"; break;
                            case 2: tbstock2.Text = Convert.ToString(int.Parse(tbstock2.Text) + BUYNUM); logger.Text += "交易成功,股票序号2,成交价格："; logger.Text += Convert.ToString(BUYPRICE); logger.Text += "\r\n"; break;
                            case 3: tbstock3.Text = Convert.ToString(int.Parse(tbstock3.Text) + BUYNUM); logger.Text += "交易成功,股票序号3,成交价格："; logger.Text += Convert.ToString(BUYPRICE); logger.Text += "\r\n"; break;
                            case 4: tbstock4.Text = Convert.ToString(int.Parse(tbstock4.Text) + BUYNUM); logger.Text += "交易成功,股票序号4,成交价格："; logger.Text += Convert.ToString(BUYPRICE); logger.Text += "\r\n"; break;
                        }
                        textBox30.Text = Convert.ToString(int.Parse(textBox30.Text) - BUYNUM * BUYPRICE);
                        Application.DoEvents();
                        WANTBUY = false;
                    }
                }
                else if (WANTSELL == true)
                {
                    //if can sell
                    if (priceStock[STOCKSELLNUM] >= SELLPRICE)
                    {
                        //update data
                        switch (STOCKSELLNUM)
                        {
                            case 0:
                                if (int.Parse(tbstock0.Text) - SELLNUM >= 0)
                                {
                                    tbstock0.Text = Convert.ToString(int.Parse(tbstock0.Text) - SELLNUM);
                                    textBox30.Text = Convert.ToString(int.Parse(textBox30.Text) + SELLNUM * SELLPRICE);
                                    logger.Text += "交易成功,股票序号0,成交价格：";
                                    logger.Text += Convert.ToString(SELLPRICE);
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                else
                                {
                                    logger.Text += "你的持仓不足，无法卖出！";
                                    //debug
                                    logger.Text += tbstock0.Text;
                                    logger.Text += "-";
                                    logger.Text += SELLNUM;
                                    logger.Text += "\r\n";
                                }
                                break;
                            case 1:
                                if (int.Parse(tbstock1.Text) - SELLNUM >= 0)
                                {
                                    tbstock1.Text = Convert.ToString(int.Parse(tbstock1.Text) - SELLNUM);
                                    textBox30.Text = Convert.ToString(int.Parse(textBox30.Text) + SELLNUM * SELLPRICE);
                                    logger.Text += "交易成功,股票序号1,成交价格：";
                                    logger.Text += Convert.ToString(SELLPRICE);
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                else
                                {
                                    logger.Text += "你的持仓不足，无法卖出！";
                                    //debug
                                    logger.Text += tbstock1.Text;
                                    logger.Text += "-";
                                    logger.Text += SELLNUM;
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                break;
                            case 2:
                                if (int.Parse(tbstock2.Text) - SELLNUM >= 0)
                                {
                                    tbstock2.Text = Convert.ToString(int.Parse(tbstock2.Text) - SELLNUM);
                                    textBox30.Text = Convert.ToString(int.Parse(textBox30.Text) + SELLNUM * SELLPRICE);
                                    logger.Text += "交易成功,股票序号2,成交价格：";
                                    logger.Text += Convert.ToString(SELLPRICE);
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                else
                                {
                                    logger.Text += "你的持仓不足，无法卖出！";
                                    //debug
                                    logger.Text += tbstock2.Text;
                                    logger.Text += "-";
                                    logger.Text += SELLNUM;
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                break;
                            case 3:
                                if (int.Parse(tbstock3.Text) - SELLNUM >= 0)
                                {
                                    tbstock3.Text = Convert.ToString(int.Parse(tbstock3.Text) - SELLNUM);
                                    textBox30.Text = Convert.ToString(int.Parse(textBox30.Text) + SELLNUM * SELLPRICE);
                                    logger.Text += "交易成功,股票序号3,成交价格：";
                                    logger.Text += Convert.ToString(SELLPRICE);
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                else
                                {
                                    logger.Text += "你的持仓不足，无法卖出！";
                                    //debug
                                    logger.Text += tbstock3.Text;
                                    logger.Text += "-";
                                    logger.Text += SELLNUM;
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                break;
                            case 4:
                                if (int.Parse(tbstock4.Text) - SELLNUM >= 0)
                                {
                                    tbstock4.Text = Convert.ToString(int.Parse(tbstock4.Text) - SELLNUM);
                                    textBox30.Text = Convert.ToString(int.Parse(textBox30.Text) + SELLNUM * SELLPRICE);
                                    logger.Text += "交易成功,股票序号4,成交价格：";
                                    logger.Text += Convert.ToString(SELLPRICE);
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                else
                                {
                                    logger.Text += "你的持仓不足，无法卖出！";
                                    //debug
                                    logger.Text += tbstock4.Text;
                                    logger.Text += "-";
                                    logger.Text += SELLNUM;
                                    logger.Text += "\r\n";
                                    WANTSELL = false;
                                }
                                break;
                        }
                        Application.DoEvents();
                    }
                }
            }));
        }

        //buy_choose
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            switch (comboBox1.Text)
            {
                case "股票A": textBox6.Text = "股票A"; break;
                case "股票B": textBox6.Text = "股票B"; break;
                case "股票C": textBox6.Text = "股票C"; break;
                case "股票D": textBox6.Text = "股票D"; break;
                case "股票E": textBox6.Text = "股票E"; break;
            }
            Application.DoEvents();
        }

        //sell_choose
        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            switch (comboBox2.Text)
            {
                case "股票A": textBox13.Text = "股票A"; break;
                case "股票B": textBox13.Text = "股票B"; break;
                case "股票C": textBox13.Text = "股票C"; break;
                case "股票D": textBox13.Text = "股票D"; break;
                case "股票E": textBox13.Text = "股票E"; break;
            }
            //calcute how many stock you can sell
            switch (comboBox2.Text)
            {
                case "股票A": textBox12.Text = tbstock0.Text; break;
                case "股票B": textBox12.Text = tbstock1.Text; break;
                case "股票C": textBox12.Text = tbstock2.Text; break;
                case "股票D": textBox12.Text = tbstock3.Text; break;
                case "股票E": textBox12.Text = tbstock4.Text; break;
            }
            Application.DoEvents();
        }


        public static bool WANTBUY = false;
        public static bool WANTSELL = false;

        public static int STOCKBUYNUM;  //the num of stock
        public static int BUYPRICE;     //your price
        public static int BUYNUM;       //how much you want to buy

        public static int STOCKSELLNUM;
        public static int SELLPRICE;
        public static int SELLNUM;

        //buy_click
        private void button1_Click(object sender, EventArgs e)
        {
            WANTBUY = true;
            BUYNUM = int.Parse(textBox8.Text);
            BUYPRICE = int.Parse(textBox9.Text);
            switch (comboBox1.Text)
            {
                case "股票A": STOCKBUYNUM = 0; break;
                case "股票B": STOCKBUYNUM = 1; break;
                case "股票C": STOCKBUYNUM = 2; break;
                case "股票D": STOCKBUYNUM = 3; break;
                case "股票E": STOCKBUYNUM = 4; break;
            }
            MessageBox.Show("成功提交买入委托！");
        }

        //sell_click
        private void button2_Click(object sender, EventArgs e)
        {
            WANTSELL = true;
            SELLNUM = int.Parse(textBox11.Text);
            SELLPRICE = int.Parse(textBox10.Text);
            switch (comboBox2.Text)
            {
                case "股票A": STOCKSELLNUM = 0; break;
                case "股票B": STOCKSELLNUM = 1; break;
                case "股票C": STOCKSELLNUM = 2; break;
                case "股票D": STOCKSELLNUM = 3; break;
                case "股票E": STOCKSELLNUM = 4; break;
            }
            MessageBox.Show("成功提交卖出委托！");
        }

        //save and close
        private void button4_Click(object sender, EventArgs e)
        {
            int[] priceStock = new int[5];
            priceStock[0] = int.Parse(textBox1.Text);
            priceStock[1] = int.Parse(textBox2.Text);
            priceStock[2] = int.Parse(textBox3.Text);
            priceStock[3] = int.Parse(textBox4.Text);
            priceStock[4] = int.Parse(textBox5.Text);

            int[] stockHold = new int[5];
            stockHold[0] = int.Parse(tbstock0.Text);
            stockHold[1] = int.Parse(tbstock1.Text);
            stockHold[2] = int.Parse(tbstock2.Text);
            stockHold[3] = int.Parse(tbstock3.Text);
            stockHold[4] = int.Parse(tbstock4.Text);

            //save
            for (int i = 0; i < 5; i++)
            {
                try
                {
                    //create database connection
                    string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=111111;";
                    MySqlConnection con = new MySqlConnection(strcon);

                    //open database
                    con.Open();

                    //sql
                    MySqlCommand cmd;
                    cmd = con.CreateCommand();

                    cmd.Parameters.AddWithValue("@stockHold_i", stockHold[i]);
                    cmd.Parameters.AddWithValue("@phonenum", login.PHONENUM);
                    cmd.CommandText = "UPDATE `itravelin`.`customer` SET `STOCK" + i + "` = @stockHold_i WHERE (`CPHONE` = @phonenum);";
                    cmd.ExecuteNonQuery();

                    cmd.Parameters.AddWithValue("@stock_i", priceStock[i]);
                    cmd.CommandText = "UPDATE `itravelin`.`stock` SET `PRICE` = @stock_i where CNAME=\"stock" + i + "\";";
                    cmd.ExecuteNonQuery();

                    cmd.Parameters.AddWithValue("@balance", textBox30.Text);
                    cmd.CommandText = "UPDATE `itravelin`.`customer` SET `BALANCE` = @balance WHERE (`CPHONE` = @phonenum);";
                    cmd.ExecuteNonQuery();

                    cmd.Parameters.AddWithValue("@totalValue", textBox29.Text);
                    cmd.CommandText = "UPDATE `itravelin`.`customer` SET `TOTALVALUE` = @totalValue WHERE (`CPHONE` = @phonenum);";
                    cmd.ExecuteNonQuery();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex + "发生异常");
                    throw;
                }
            }

            //close
            this.Close();
        }

        //calcute how many stock you can buy
        private void textBox9_TextChanged(object sender, EventArgs e)
        {
            string str = textBox9.Text;//avoid intParseError caused by empty textbox9
            int balance;
            int price=-1;

            if (str == "") balance = 0;
            else price = int.Parse(textBox9.Text);

            balance = int.Parse(textBox30.Text);

            int canBuy = balance / price;
            textBox7.Text = Convert.ToString(canBuy);
        }
    }
}

register（注册过程）

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;
/* 电话号码不能重复
 * 性别有位数限制
 * 年龄有位数限制
 */

namespace traveling
{
    public partial class register : Form
    {
        public register()
        {
            InitializeComponent();
        }


        private void okbtn_Click(object sender, EventArgs e)
        {
            Customer customer = new Customer();

            //Console.WriteLine("1");
            string name = Convert.ToString(nametxt.Text);
            string password = Convert.ToString(passwordtxt.Text);
            string age = Convert.ToString(agetxt.Text);
            string id = Convert.ToString(idtxt.Text);
            string sex = Convert.ToString(sextxt.Text);
            string phone = Convert.ToString(phonetxt.Text);
            string email = Convert.ToString(emailtxt.Text);

            string totalvalue = Convert.ToString(1000000);  //initial 1000000yuan
            string balance = Convert.ToString(1000000);     //initial 1000000yuan

            if (FunctionDefine.Isempty(name))
            {
                MessageBox.Show("姓名不能为空！");
                return;
            }
            if (FunctionDefine.Isempty(password))
            {
                MessageBox.Show("密码不能为空！");
                return;
            }
            if (FunctionDefine.Isempty(id))
            {
                MessageBox.Show("身份证号不能为空！");
                return;
            }
            if (FunctionDefine.Isempty(phone))
            {
                MessageBox.Show("手机号不能为空！");
                return;
            }

            string strcon = "server=localhost;port=3306;database=itravelin;user=root;password=g66666666;";
            MySqlConnection con = new MySqlConnection(strcon);
            MySqlCommand cmd;
            con.Open();
            cmd = con.CreateCommand();
            cmd.CommandText = "select * from itravelin.customer where cphone = " + phone + ";";//find this phonenum
            string debugger = (string)cmd.ExecuteScalar();//if not find, return null
            if (debugger != null) MessageBox.Show("此手机号已被注册！");
            else
            {
                try
                {
                    cmd.Parameters.AddWithValue("@name", name);
                    cmd.Parameters.AddWithValue("@age", age);
                    cmd.Parameters.AddWithValue("@sex", sex);
                    cmd.Parameters.AddWithValue("@id", id);
                    cmd.Parameters.AddWithValue("@phone", phone);
                    cmd.Parameters.AddWithValue("@password", password);
                    cmd.Parameters.AddWithValue("@email", email);

                    cmd.Parameters.AddWithValue("@totalvalue", totalvalue);
                    cmd.Parameters.AddWithValue("@balance", balance);

                    cmd.CommandText = "insert into itravelin.customer values(@name,@age,@sex,@id,@phone,@password,@email,@totalvalue,@balance,\"0\",\"0\",\"0\",\"0\",\"0\");";//和上面七行无关顺序

                    int ret = cmd.ExecuteNonQuery();//debug execute two times
                    if (ret > 0) MessageBox.Show("注册成功！");
                    else MessageBox.Show("注册失败！");
                }
                catch (Exception)
                {
                    MessageBox.Show("出现异常");
                    throw;
                }
                finally
                {
                    if (con.State == ConnectionState.Open)
                    {
                        con.Close();

                    }
                }
            }
        }
    }
}