using 

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;
using MySql.Data.MySqlClient;namespace C_sharp学生信息管理系统
{public partial class Form2 : Form{String connetStr =          //连接数据库字符串"server=localhost;port=3306;user=root;password=123456; database=studentsql;";public Form2(){InitializeComponent();//设置窗口显示位置居中this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;}//注册按钮点击事件private void button1_Click(object sender, EventArgs e){//检查注册的用户名和密码是否为空if (textBox1.Text.Length < 4){MessageBox.Show("用户名不可少于4位！");return;}if ((textBox2.Text.Length < 4) || (textBox3.Text.Length < 4)){MessageBox.Show("注册密码不可少于4位！");return;}//检查两次密码输入是否一致if(textBox2.Text != textBox3.Text){MessageBox.Show("两次密码输入不一致！");return;}try{//将box1中的文本和box2中的文本插入到管理员数据表中MySqlConnection conn = new MySqlConnection(connetStr);conn.Open();String sql ="INSERT INTO account VALUE(" + textBox1.Text + "," + textBox3.Text + "); ";MySqlCommand cmd = new MySqlCommand(sql, conn);cmd.ExecuteNonQuery();//弹出提示框MessageBox.Show("注册成功！");//进入操作界面Form1 form1 = new Form1();form1.Show();this.Hide();    //隐藏当前窗口}catch{MessageBox.Show("用户名已存在或其他错误！");return;}}//窗口退出之后事件，该窗口退出后程序退出private void Form2_FormClosed(object sender, FormClosedEventArgs e){Application.Exit();}//隐藏密码单选框被选中时，密码框设置掩码private void radioButton1_CheckedChanged(object sender, EventArgs e){textBox2.PasswordChar = '#';textBox3.PasswordChar = '#';}}
}

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;
using MySql.Data.MySqlClient;namespace C_sharp学生信息管理系统
{public partial class Form3 : Form{String connetStr =          //连接数据库字符串"server=localhost;port=3306;user=root;password=123456; database=studentsql;";MySqlConnection conn;       //操作数据库使用的对象MySqlCommand cmd;String nameid;              //临时记录数据表id列字段int index_y;                //记录选中当前行索引int index_x;                //记录选中当前列索引String sql;                 //执行的sql语句字符串//构造public Form3(){InitializeComponent();//设置窗口显示位置居中this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;queryop();}//该窗体关闭后，程序退出private void Form3_FormClosing(object sender, FormClosingEventArgs e){Application.Exit();}//刷新：查询并将结果填充到表格private void queryop(){try{//将数据表中的信息填充到表格控件中conn = new MySqlConnection(connetStr);conn.Open();sql = "select * from studentmess;";cmd = new MySqlCommand(sql, conn);MySqlDataAdapter adapter = new MySqlDataAdapter(sql, conn);DataTable dataTable = new DataTable();adapter.Fill(dataTable);    //将adapter中的信息填充到表格中dataGridView1.DataSource = dataTable;dataGridView1.AutoGenerateColumns = true;dataGridView1.DataSource = dataTable;}catch{MessageBox.Show("意料之外的错误！");return;}}//点击查询按钮执行查询private void button1_Click(object sender, EventArgs e){queryop();}//限定日期添加规则函数private String addruletime(){//如果当前列不是日期列返回默认日期字符串//否则不变String timetemp;if (index_x != 2)timetemp = "2020/1/1";elsetimetemp = dataGridView1.Rows[index_y].Cells[2].Value.ToString();return timetemp;}//限定成绩添加函数private String addrulescore(){//如果当前列不是三个成绩列，则返回默认成绩，否则不变String tempscore;int tempx = 0;          //临时记录列if (index_x != 5 || index_x != 6 || index_x != 7){tempscore = "0";return tempscore;   //不是成绩列直接返回}//是成绩列判断是那一列，然后根据列返回switch (index_x){case 5:tempx = 5;break;case 6:tempx = 6;break;case 7:tempx = 7;break;}tempscore = dataGridView1.Rows[index_y].Cells[tempx].Value.ToString();return tempscore;}//当前所选内容更改时发生private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e){//更改内容包括更改和添加新行//首先尝试添加新行，但如果要添加新行，此时更改的行坐标对应的姓名等信息不存在，所以程序抛出异常//这时转为在数据库中插入新行操作try{//获取当前行的索引index_y = dataGridView1.CurrentRow.Index;//连接数据库服务conn = new MySqlConnection(connetStr);  //conn new新对象时，会自动调用关闭数据库连接函数conn.Open();//获取当前选中行的每一个数据，并修改到数据库//执行的sql语句sql ="UPDATE studentmess SET " +"id = " + dataGridView1.Rows[index_y].Cells[0].Value.ToString() + "," +"`name` = '" + dataGridView1.Rows[index_y].Cells[1].Value.ToString() + "'," +"birthday = '" + dataGridView1.Rows[index_y].Cells[2].Value.ToString() + "'," +"idcardnum = '" + dataGridView1.Rows[index_y].Cells[3].Value.ToString() + "'," +"contact = '" + dataGridView1.Rows[index_y].Cells[4].Value.ToString() + "'," +"`C# score` = " + dataGridView1.Rows[index_y].Cells[5].Value.ToString() + "," +"` C++ score` = " + dataGridView1.Rows[index_y].Cells[6].Value.ToString() + "," +"`Data structure score` = " + dataGridView1.Rows[index_y].Cells[7].Value.ToString() +" WHERE id = '" + nameid + "';";cmd = new MySqlCommand(sql, conn);cmd.ExecuteNonQuery();      //执行sql语句}catch{//尝试添加新的行//如果再次出现异常代表，没有从id(主键)列开始添加行，弹出提示框try{//连接数据库conn = new MySqlConnection(connetStr);conn.Open();//根据规则执行sql ="INSERT INTO `studentmess` VALUES(" +dataGridView1.Rows[index_y].Cells[0].Value.ToString() + "," +"'" + dataGridView1.Rows[index_y].Cells[1].Value.ToString() + "'," +"'" + addruletime() + "'," +"'" + dataGridView1.Rows[index_y].Cells[3].Value.ToString() + "'," +"'" + dataGridView1.Rows[index_y].Cells[4].Value.ToString() + "'," +"'" + addrulescore() + "'," +"'" + addrulescore() + "'," +"'" + addrulescore() + "'" +"); ";cmd = new MySqlCommand(sql, conn);cmd.ExecuteNonQuery();      //执行sql语句}catch{MessageBox.Show("t操作无效！n没有在id列开始添加新行或其他错误");return;}}}//单元格编辑模式启动时发生private void dataGridView1_CellBeginEdit(object sender, DataGridViewCellCancelEventArgs e){//获取编辑单元格前的单元格行索引index_y = dataGridView1.CurrentRow.Index;//列索引index_x = dataGridView1.ColumnCount;//记录开始的id信息，用于更改后在数据库中查找对应idnameid = dataGridView1.Rows[index_y].Cells[0].Value.ToString();}//删除按钮点击事件private void button2_Click(object sender, EventArgs e){try{//获取当前行列索引index_y = dataGridView1.CurrentRow.Index;conn = new MySqlConnection(connetStr);conn.Open();//sql语句sql ="DELETE FROM studentmess WHERE id = "+ dataGridView1.Rows[index_y].Cells[0].Value.ToString() + ";";cmd = new MySqlCommand(sql, conn);cmd.ExecuteNonQuery();      //执行sql语句}catch (Exception){MessageBox.Show("意料之外的错误！");}finally{queryop();  //刷新数据}}//单击文本框事件private void textBox1_Click(object sender, EventArgs e){//将文本内容清除textBox1.Text = "";}//执行按钮点击事件private void button3_Click(object sender, EventArgs e){try{//输入执行语句功能，不能显示查询语句conn = new MySqlConnection(connetStr);conn.Open();sql = textBox1.Text;cmd = new MySqlCommand(sql, conn);cmd.ExecuteNonQuery();      //执行sql语句MessageBox.Show("执行成功！");}catch{MessageBox.Show("sql语法错误！");}finally{queryop();      //刷新表格}}}
}