c#------学生管理系统

学生管理系统的流程图以及实现功能：
先说，数据库知识：

DROP DATABASE IF EXISTS FinalLogin;  

CREATE DATABASE FinalLogin;  

USE FinalLogin;

DROP TABLE IF EXISTS SC
DROP TABLE IF EXISTS Student
DROP TABLE IF EXISTS Course
DROP TABLE IF EXISTS SysUser

CREATE TABLE SysUser           /*用户登记表*/
 (	
 UserID NCHAR(20) PRIMARY KEY,                          
 UserPassWord NCHAR(32) ,
 UserName NCHAR(20),  
 UserSex char(2) check (UserSex in ('男','女')) default('女'),
 UserBirthday datetime,
 UserMobile NCHAR(11),
 UserMajor NCHAR(20),
 UserPhoto image
 ); 

 CREATE TABLE Student          /*学生记录表*/
 (	
 Sno CHAR(9) PRIMARY KEY,        /* 列级完整性约束条件,Sno是主码*/                  
 Sname CHAR(20) UNIQUE,             /* Sname取唯一值*/
 Ssex CHAR(2) check (SSex in ('男','女')) default('女'),
 Sage SMALLINT,
 Sdept CHAR(20)
 ); 

CREATE TABLE  Course             /*课程表*/
 (	
 Cno CHAR(4) PRIMARY KEY,
 Cname CHAR(40),            
 Cpno CHAR(4),               	                      
 Ccredit SMALLINT,
 FOREIGN KEY (Cpno) REFERENCES  Course(Cno) 
 ); 
  
CREATE TABLE  SC       /*成绩表*/
 (
 Sno CHAR(9), 
 Cno CHAR(4),  
 Grade SMALLINT,
 PRIMARY KEY (Sno,Cno),                     /* 主码由两个属性构成，必须作为表级完整性进行定义*/
 FOREIGN KEY (Sno) REFERENCES Student(Sno),  /* 表级完整性约束条件，Sno是外码，被参照表是Student */
 FOREIGN KEY (Cno)REFERENCES Course(Cno)     /* 表级完整性约束条件， Cno是外码，被参照表是Course*/
 ); 



INSERT  INTO  Student (Sno,Sname,Ssex,Sdept,Sage) VALUES ('201215121','李勇','男','CS',20);
INSERT  INTO  Student (Sno,Sname,Ssex,Sdept,Sage) VALUES ('201215122','刘晨','女','CS',19);
INSERT  INTO  Student (Sno,Sname,Ssex,Sdept,Sage) VALUES ('201215123','王敏','女','MA',18);
INSERT  INTO  Student (Sno,Sname,Ssex,Sdept,Sage) VALUES ('201215125','张立','男','IS',19);
INSERT  INTO  Student (Sno,Sname,Ssex,Sdept,Sage) VALUES ('201215128','陈冬','男','IS',20);

SELECT * FROM Student

INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('1','数据库',NULL,4);
INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('2','数学',NULL,4);
INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('3','信息系统',NULL,4);
INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('4','操作系统',NULL,4);
INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('5','数据结构',NULL,4);
INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('6','数据处理',NULL,4);
INSERT  INTO Course(Cno,Cname,Cpno,Ccredit)	VALUES ('7','Pascal语言',NULL,4);

UPDATE Course SET Cpno = '5' WHERE Cno = '1' 
UPDATE Course SET Cpno = '1' WHERE Cno = '3' 
UPDATE Course SET Cpno = '6' WHERE Cno = '4' 
UPDATE Course SET Cpno = '7' WHERE Cno = '5' 
UPDATE Course SET Cpno = '6' WHERE Cno = '7' 

SELECT * FROM Course

INSERT  INTO SC(Sno,Cno,Grade) VALUES ('201215121 ','1',92);
INSERT  INTO SC(Sno,Cno,Grade) VALUES ('201215121 ','2',85);
INSERT  INTO SC(Sno,Cno,Grade) VALUES ('201215121 ','3',88);
INSERT  INTO SC(Sno,Cno,Grade) VALUES ('201215122 ','2',90);
INSERT  INTO SC(Sno,Cno,Grade) VALUES ('201215122 ','3',80);

SELECT * FROM SC

IF(OBJECT_ID('regist_recorder') is not null)        -- 判断名为 regist_recorder 的触发器是否存在
DROP TRIGGER regist_recorder        -- 删除触发器
GO

CREATE TRIGGER regist_recorder
ON SysUser  	         
AFTER
INSERT
AS 
	declare @UserName    nchar(20)
	declare @DateTime    datetime
	declare @UserOperation nchar(200)

	select @UserName = system_user
	select @DateTime = CONVERT(datetime,GETDATE(),120) 

	declare @op varchar(10)
	select @op=case when exists(select 1 from inserted) and exists(select 1 from deleted)
                   then 'Update'
                   when exists(select 1 from inserted) and not exists(select 1 from deleted)
                   then 'Insert'
                   when not exists(select 1 from inserted) and exists(select 1 from deleted)
                   then 'Delete' end
                   
	
	select @UserOperation = @op

VS中代码：
全局变量

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Student_System
{
    class Class1
    {
        public static string totalID;
        public static string Mobile;
    }
}

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 Student_System
{
    public partial class 学生系统 : Form
    {
        public 学生系统()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            STUDENT stu = new STUDENT();
            stu.Show();
            this.Hide();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            TEACHER tea = new TEACHER();
            tea.Show();
            this.Hide();
        }

        private void 学生系统_Load(object sender, EventArgs e)
        {

        }
    }
}

学生端：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class STUDENT : Form
    {
        public STUDENT()
        {
            InitializeComponent();
        }

        private void label3_Click(object sender, EventArgs e)
        {

        }

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

        private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            RESGISTER res = new RESGISTER();
            res.Show();
            
        }
        public string code;
        private void STUDENT_Load(object sender, EventArgs e)
        {
            //随机实例化 
            Random ran = new Random();
            int number;
            char code1;
            //取五个数 
            for (int i = 0; i < 5; i++)
            {
                number = ran.Next();
                if (number % 2 == 0)
                    code1 = (char)('0' + (char)(number % 10));
                else
                    code1 = (char)('A' + (char)(number % 26)); //转化为字符 

                this.code += code1.ToString();
            }

            label5.Text = code;
        }

        protected void button1_Click(object sender, EventArgs e)  //登录
        {
            string userID = textBox1.Text.Trim();  //取出账号
            string password = EncryptWithMD5(textBox2.Text.Trim());  //取出密码并加密
            Class1.totalID = userID;

            //string connstr = ConfigurationManager.ConnectionStrings["connectionString"].ToString(); //读取连接字符串
            string myConnString = "Data Source=.;Initial Catalog=FinalLogin;Persist Security Info=True;User ID=sa;Password=123456";

            SqlConnection sqlConnection = new SqlConnection(myConnString);  //实例化连接对象
            sqlConnection.Open();

            string sql = "select UserID,UserPassword from SysUser where UserID = '" + userID + "' and UserPassword = '" + password + "'";                                            //编写SQL命令
            SqlCommand sqlCommand = new SqlCommand(sql, sqlConnection);

            SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();

            if (sqlDataReader.HasRows && textBox3.Text == code)
            {
                MessageBox.Show("欢迎使用！");             //登录成功
                StuMain form2 = new StuMain();
                form2.Show();
               
            }
            else
            {
                MessageBox.Show("登录失败！");
                return;
            }
            sqlDataReader.Close();
            sql = "insert into SysLog values ( '" + userID + "' , '" + DateTime.Now + "' , '" + "Login" + "')";          //编写SQL命令

            sqlCommand = new SqlCommand(sql, sqlConnection);
            sqlCommand.ExecuteNonQuery();
            sqlConnection.Close();

        }
        public static string EncryptWithMD5(string source)
        {
            byte[] sor = Encoding.UTF8.GetBytes(source);
            MD5 md5 = MD5.Create();
            byte[] result = md5.ComputeHash(sor);
            StringBuilder strbul = new StringBuilder(40);
            for (int i = 0; i < result.Length; i++)
            {
                strbul.Append(result[i].ToString("x2"));//加密结果"x2"结果为32位,"x3"结果为48位,"x4"结果为64位
            }
            return strbul.ToString();
        }


        public Byte[] mybyte = new byte[0];
        private void textBox1_Leave(object sender, EventArgs e)   //当鼠标离开ID框时
        {
            try
            {
                string connString = "Data Source=.;Initial Catalog=FinalLogin;Persist Security Info=True;User ID=sa;Password=123456";//数据库连接字符串
                SqlConnection connection = new SqlConnection(connString);//创建connection对象

                //打开数据库连接
                connection.Open();
                //创建SQL语句
                string sql = "select UserPhoto from SysUser where UserID = '" + textBox1.Text + "'";
                //创建SqlCommand对象
                SqlCommand command = new SqlCommand(sql, connection);
                //创建DataAdapter对象
                SqlDataAdapter dataAdapter = new SqlDataAdapter(command);
                //创建DataSet对象
                DataSet dataSet = new DataSet();
                dataAdapter.Fill(dataSet, "SysUser");
                int c = dataSet.Tables["SysUser"].Rows.Count;
                if (c > 0)
                {
                    Byte[] mybyte = new byte[0];
                    mybyte = (Byte[])(dataSet.Tables["SysUser"].Rows[c - 1]["UserPhoto"]);
                    MemoryStream ms = new MemoryStream(mybyte);
                    pictureBox1.Image = Image.FromStream(ms);
                }
                else
                    pictureBox1.Image = null;
                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

        }

        private void pictureBox1_Click(object sender, EventArgs e)   //插入图片
        {

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void linkLabel2_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {

            StuPassword stuPassword = new StuPassword();
            stuPassword.Show();
        }
    }
}

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 Student_System
{
    public partial class StuMain : Form
    {
        public StuMain()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            StuMessage sm = new StuMessage();
            sm.Show();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            StuGrade sg = new StuGrade();
            sg.Show();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            StuProject sp = new StuProject();
            sp.Show();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class StuMessage : Form
    {
        public StuMessage()
        {
            InitializeComponent();
        }

        private void label8_Click(object sender, EventArgs e)  //学号
        {
            
        }

        private void label9_Click(object sender, EventArgs e) //姓名
        {
          
        }

        private void label10_Click(object sender, EventArgs e)
        {
           
        }

        private void label11_Click(object sender, EventArgs e)
        {
         
        }



        private void label12_Click(object sender, EventArgs e)
        {
          
        }

        private void label13_Click(object sender, EventArgs e)
        {
            
        }

        private void StuMessage_Load(object sender, EventArgs e)
        {
            
            label8.Text = Class1.totalID;
            try
            {
                string connString = "Data Source=.;Initial Catalog=FinalLogin;Persist Security Info=True;User ID=sa;Password=123456";//数据库连接字符串
                SqlConnection connection = new SqlConnection(connString);//创建connection对象

                //打开数据库连接
                connection.Open();
                //创建SQL语句
                string sql = "select UserName,UserSex,UserBirthday,UserMobile,UserMajor,UserPhoto from SysUser where UserID = '" + Class1.totalID + "'";
                //创建SqlCommand对象
                SqlCommand command = new SqlCommand(sql, connection);
                //创建DataAdapter对象
                SqlDataAdapter dataAdapter = new SqlDataAdapter(command);
                //创建DataSet对象
                dataAdapter.SelectCommand = command;

                DataSet dt = new DataSet();
                dataAdapter.Fill(dt);
                int b = dt.Tables[0].Rows.Count;
                if (b > 0)
                {
                    label9.Text = dt.Tables[0].Rows[0]["username"].ToString();
                    label10.Text = dt.Tables[0].Rows[0]["usersex"].ToString();
                    label11.Text = dt.Tables[0].Rows[0]["userbirthday"].ToString();
                    label12.Text = dt.Tables[0].Rows[0]["usermajor"].ToString();
                    label13.Text = dt.Tables[0].Rows[0]["usermobile"].ToString();
                    Class1.Mobile = label13.Text;
                }
               
                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

            try
            {
                string connString = "Data Source=.;Initial Catalog=FinalLogin;Persist Security Info=True;User ID=sa;Password=123456";//数据库连接字符串
                SqlConnection connection = new SqlConnection(connString);//创建connection对象

                //打开数据库连接
                connection.Open();
                //创建SQL语句
                string sql = "select UserPhoto from SysUser where UserID = '" + Class1.totalID + "'";
                //创建SqlCommand对象
                SqlCommand command = new SqlCommand(sql, connection);
                //创建DataAdapter对象
                SqlDataAdapter dataAdapter = new SqlDataAdapter(command);
                //创建DataSet对象
                DataSet dataSet = new DataSet();
                dataAdapter.Fill(dataSet, "SysUser");
                int c = dataSet.Tables["SysUser"].Rows.Count;
                if (c > 0)
                {
                    Byte[] mybyte = new byte[0];
                    mybyte = (Byte[])(dataSet.Tables["SysUser"].Rows[c - 1]["UserPhoto"]);
                    MemoryStream ms = new MemoryStream(mybyte);
                    pictureBox1.Image = Image.FromStream(ms);
                }
                else
                    pictureBox1.Image = null;
                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
          
        }

        private void button1_Click(object sender, EventArgs e)
        {
            ChageMobile cm = new ChageMobile();
            cm.Show();
        }

        private void button3_Click(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            this.Dispose();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class StuProject : Form
    {
        public StuProject()
        {
            InitializeComponent();
        }

        private void StuProject_Load(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“finalLoginDataSet3.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter1.Fill(this.finalLoginDataSet3.Course);
           
            // TODO: 这行代码将数据加载到表“finalLoginDataSet1.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet1.Course);
            

        }

       

        private void button1_Click(object sender, EventArgs e)   //加课
        {
            string Cno = textBox1.Text.Trim();
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
         
                con.Open();
                string insertStr = "INSERT INTO SC(Sno,Cno)   " +"VALUES ('" + Class1.totalID + "','" + Cno + "')";
                SqlCommand cmd = new SqlCommand(insertStr, con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("更改成功！");
                con.Dispose();
        
           
          
        }

        private void button2_Click(object sender, EventArgs e)
        {
           
         
        }

        private void button4_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class RESGISTER : Form
    {
        public RESGISTER()
        {
            InitializeComponent();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }
        public Byte[] mybyte = new byte[0];
        private void button1_Click(object sender, EventArgs e)  //上传图片
        {
            //打开浏览图片对话框
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.ShowDialog();
            string picturePath = openFileDialog.FileName;//获取图片路径
            //文件的名称，每次必须更换图片的名称，这里很为不便
            //创建FileStream对象
            FileStream fs = new FileStream(picturePath, FileMode.Open, FileAccess.Read);
            //声明Byte数组
            mybyte = new byte[fs.Length];
            //读取数据
            fs.Read(mybyte, 0, mybyte.Length);
            pictureBox1.Image = Image.FromStream(fs);
            fs.Close();
        }

        public static string EncryptWithMD5(string source)
        {
            byte[] sor = Encoding.UTF8.GetBytes(source);
            MD5 md5 = MD5.Create();
            byte[] result = md5.ComputeHash(sor);
            StringBuilder strbul = new StringBuilder(40);
            for (int i = 0; i < result.Length; i++)
            {
                strbul.Append(result[i].ToString("x2"));//加密结果"x2"结果为32位,"x3"结果为48位,"x4"结果为64位
            }
            return strbul.ToString();
        }

        private void button2_Click(object sender, EventArgs e)
        {
        
            try
            {
                string connString = "Data Source=.;Initial Catalog=FinalLogin;Persist Security Info=True;User ID=sa;Password=123456";//数据库连接字符串
                SqlConnection connection = new SqlConnection(connString);//创建connection对象
                String sql = "insert into SysUser (UserID,UserPassWord,UserName,UserSex,UserBirthday,UserMobile,UserMajor ,UserPhoto ) " +
                                                        "values (@userid, @userpassword,@username,@usersex,@userbirthday,@usermobile,@usermajor,@userphoto)";
                SqlCommand command = new SqlCommand(sql, connection);

                SqlParameter sqlParameter = new SqlParameter("@userid", textBox1.Text);
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@userpassword", EncryptWithMD5(textBox4.Text));
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@username", textBox3.Text);
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@usersex", comboBox1.Text);
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@userbirthday", dateTimePicker1.Value);
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@usermobile", textBox2.Text);
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@usermajor", textBox5.Text);
                command.Parameters.Add(sqlParameter);
                sqlParameter = new SqlParameter("@userphoto", SqlDbType.VarBinary, mybyte.Length, ParameterDirection.Input, false, 0, 0, null, DataRowVersion.Current, mybyte);
                command.Parameters.Add(sqlParameter);

                
                //打开数据库连接
                connection.Open();
                command.ExecuteNonQuery();
                connection.Close();
                MessageBox.Show("register succeed");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }


            this.Close();
        }

        private void RESGISTER_Load(object sender, EventArgs e)
        {
          
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {

        }

        private void textBox1_Leave(object sender, EventArgs e)
        {
            String ID = textBox1.Text.Trim();
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
           con.Open();

            string sql = "select * from Student where Sno = '" + ID + "'";                                            //编写SQL命令
            SqlCommand sqlCommand = new SqlCommand(sql, con);

            SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();
            if (sqlDataReader.HasRows)
            {
            }
            else
            {
                MessageBox.Show("ID账号不匹配！");
                return;
            }
            sqlDataReader.Close();
            sqlCommand.ExecuteNonQuery();
            con.Close();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class StuPassword : Form
    {
        public StuPassword()
        {
            InitializeComponent();
        }
        public string code;
        private void StuPassword_Load(object sender, EventArgs e)
        {
            //随机实例化 
            Random ran = new Random();
            int number;
            char code1;
            //取五个数 
            for (int i = 0; i < 5; i++)
            {
                number = ran.Next();
                if (number % 2 == 0)
                    code1 = (char)('0' + (char)(number % 10));
                else
                    code1 = (char)('A' + (char)(number % 26)); //转化为字符 

                this.code += code1.ToString();
            }

            label7.Text = code;
        }
        public static string EncryptWithMD5(string source)
        {
            byte[] sor = Encoding.UTF8.GetBytes(source);
            MD5 md5 = MD5.Create();
            byte[] result = md5.ComputeHash(sor);
            StringBuilder strbul = new StringBuilder(40);
            for (int i = 0; i < result.Length; i++)
            {
                strbul.Append(result[i].ToString("x2"));//加密结果"x2"结果为32位,"x3"结果为48位,"x4"结果为64位
            }
            return strbul.ToString();
        }

        private void button1_Click(object sender, EventArgs e)  //确认
        {
            String UserID = textBox1.Text.Trim();
            String UserMobile = textBox2.Text.Trim();
            String UserPassword = textBox3.Text.Trim();
           
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
     
           
            if ( textBox5.Text == code)
            {
                con.Open();
                string password = EncryptWithMD5(textBox3.Text.Trim());
                string insertStr = "UPDATE SysUser SET UserPassword='" + password + "' WHERE UserID ='" + UserID + "' AND UserMobile='" + UserMobile + "'";

                SqlCommand cmd = new SqlCommand(insertStr, con);
                
                
                cmd.ExecuteNonQuery();
                con.Close();
                MessageBox.Show("更改成功！");
                    
            }
            con.Dispose();
            
            
        }

        private void textBox4_Leave(object sender, EventArgs e)
        {
            String UserOldMobile = textBox3.Text.Trim();
            String UserNewMobile = textBox4.Text.Trim();
            if (UserOldMobile == UserNewMobile)
            {
            }
            else
            {
                MessageBox.Show("密码不一样");
                textBox4.Text = null;
                
            }
        }

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

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class ChageMobile : Form
    {
        public ChageMobile()
        {
            InitializeComponent();
        }

        public string code;
        private void ChageMobile_Load(object sender, EventArgs e)
        {
            //随机实例化 
            Random ran = new Random();
            int number;
            char code1;
            //取五个数 
            for (int i = 0; i < 5; i++)
            {
                number = ran.Next();
                if (number % 2 == 0)
                    code1 = (char)('0' + (char)(number % 10));
                else
                    code1 = (char)('A' + (char)(number % 26)); //转化为字符 

                this.code += code1.ToString();
            }

            label5.Text = code;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            String UserOldMobile = textBox1.Text.Trim();
            String UserNewMobile = textBox2.Text.Trim();

            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
                if(textBox4.Text == code &&UserOldMobile==Class1.Mobile)
                {
                    con.Open();
                    string insertStr = "UPDATE SysUser SET UserMobile='" + UserNewMobile + "' WHERE UserMobile ='" + UserOldMobile + "'";
                    SqlCommand cmd = new SqlCommand(insertStr, con);
                    cmd.ExecuteNonQuery();
                    MessageBox.Show("更改成功！");
                    this.Close();
                }
               
            }
            catch
            {
                MessageBox.Show("输入数据违反要求！");
            }
            finally
            {
                con.Dispose();
            }
           
        }

        private void textBox3_Leave(object sender, EventArgs e)
        {
            String UserOldMobile = textBox2.Text.Trim();
            String UserNewMobile = textBox3.Text.Trim();
            if (UserOldMobile==UserNewMobile)
            {
            }
            else
            {
                MessageBox.Show("密码不一样");
                textBox3.Focus();
            }
        }

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

教师端：

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 Student_System
{
    public partial class TEACHER : Form
    {
        public TEACHER()
        {
            InitializeComponent();
        }

        public string code;
        private void TEACHER_Load(object sender, EventArgs e)
        {
            //随机实例化 
            Random ran = new Random();
            int number;
            char code1;
            //取五个数 
            for (int i = 0; i < 5; i++)
            {
                number = ran.Next();
                if (number % 2 == 0)
                    code1 = (char)('0' + (char)(number % 10));
                else
                    code1 = (char)('A' + (char)(number % 26)); //转化为字符 

                this.code += code1.ToString();
            }

            label5.Text = code;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string ID = textBox1.Text.Trim();
            string Password = textBox2.Text.Trim();
            if (ID == "admin" && Password == "123" && textBox3.Text == code)
            {
                MessageBox.Show("欢迎使用！");
                TeaMain teaMain = new TeaMain();
                teaMain.Show();
            }
        }
    }
}

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 Student_System
{
    public partial class TeaMain : Form
    {
        public TeaMain()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            TeaMessage teaMessage = new TeaMessage();
            teaMessage.Show();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            TeaCourse teaCourse = new TeaCourse();
            teaCourse.Show();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            TeaGrade teaGrade = new TeaGrade();
            teaGrade.Show();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class TeaMessage : Form
    {
        public TeaMessage()
        {
            InitializeComponent();
        }

        private void TeaMessage_Load(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“finalLoginDataSet8.Student”中。您可以根据需要移动或删除它。
            this.studentTableAdapter.Fill(this.finalLoginDataSet8.Student);
            // TODO: 这行代码将数据加载到表“finalLoginDataSet7.SysUser”中。您可以根据需要移动或删除它。
            this.sysUserTableAdapter.Fill(this.finalLoginDataSet7.SysUser);

        }

        private void button1_Click(object sender, EventArgs e)   //增加
        {
            String Sno = textBox1.Text.Trim();
            String Sname = textBox2.Text.Trim();
            String Ssex = textBox3.Text.Trim();
            String Sage = textBox4.Text.Trim();
            String Sdept = textBox5.Text.Trim();
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
                con.Open();
                string insertStr = "INSERT INTO Student(Sno,Sname,Ssex,Sage,Sdept)   " +
                    "VALUES ('" + Sno + "','" + Sname + "','" + Ssex + "','" + Sage +"','"+Sdept+ "')";
                SqlCommand cmd = new SqlCommand(insertStr, con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("添加成功！");
            }
            catch
            {
                MessageBox.Show("输入数据违反要求！");
            }
            finally
            {
                con.Dispose();
            }
            // TODO: 这行代码将数据加载到表“finalLoginDataSet8.Student”中。您可以根据需要移动或删除它。
            this.studentTableAdapter.Fill(this.finalLoginDataSet8.Student);
        }

        private void button2_Click(object sender, EventArgs e)   //删除
        {
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
                con.Open();
                string select_id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
                //选择的当前行第一列的值，也就是Sno
                string delete_by_id = "delete from Student where Sno=" + select_id;
                //删除语句
                SqlCommand cmd = new SqlCommand(delete_by_id, con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("删除成功！");
                // TODO: 这行代码将数据加载到表“finalLoginDataSet8.Student”中。您可以根据需要移动或删除它。
                this.studentTableAdapter.Fill(this.finalLoginDataSet8.Student);

            }
            catch
            {
                MessageBox.Show("请选择正确的行！");
            }
            finally
            {
                con.Dispose();

            }
            // TODO: 这行代码将数据加载到表“finalLoginDataSet8.Student”中。您可以根据需要移动或删除它。
            this.studentTableAdapter.Fill(this.finalLoginDataSet8.Student);
        }

       

        private void button4_Click(object sender, EventArgs e)   //查找
        {
            String Sno = textBox1.Text.Trim();
            String Sname = textBox2.Text.Trim();
            String Ssex = textBox3.Text.Trim();
            String Sage = textBox4.Text.Trim();
            String Sdept = textBox5.Text.Trim();
            
           
            String conn = "Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456";
            SqlConnection sqlConnection = new SqlConnection(conn);  //实例化连接对象
            try
            {

                if (Sno != "")
                {
                    sqlConnection.Open();
                    String select_by_id = "select * from Student where Sno='" + Sno + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }
                else if (Sname != "")
                {
                    sqlConnection.Open();
                    String select_by_id = "select * from Student where Sname='" + Sname + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }

                else if (Ssex != "")
                {
                    sqlConnection.Open();
                    String select_by_id = "select * from Student where Ssex='" + Ssex + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }

                else if (Sage != "")
                {
                    sqlConnection.Open();
                    String select_by_id = "select * from Student where Sage='" + Sage + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }

                else if (Sdept != "")
                {
                    sqlConnection.Open();
                    String select_by_id = "select * from Student where Sdept='" + Sdept + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }

                else 
                {
                    sqlConnection.Open();
                    String select_by_id = "select * from Student";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }


                // sqlDataReader.Close();
                //cmd.ExecuteNonQuery();
                MessageBox.Show("查找成功！");

            }
            catch
            {
                MessageBox.Show("查询语句有误，请认真检查SQL语句！");
            }
            finally
            {
                sqlConnection.Dispose();
            }
        }

        private void button3_Click_1(object sender, EventArgs e)  //完成
        {
            this.Close();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class TeaGrade : Form
    {
        public TeaGrade()
        {
            InitializeComponent();
        }

        private void TeaGrade_Load(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“finalLoginDataSet4.SC”中。您可以根据需要移动或删除它。
            this.sCTableAdapter.Fill(this.finalLoginDataSet4.SC);

        }

        private void button1_Click(object sender, EventArgs e)
        {
            String Sno = textBox1.Text.Trim();
            String Cno = textBox2.Text.Trim();
            String Grade = textBox3.Text.Trim();

            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
                con.Open();
                string insertStr = "UPDATE SC SET Grade='" + Grade + "' WHERE Sno ='" + Sno +"'AND Cno='" + Cno + "'";
                
                SqlCommand cmd = new SqlCommand(insertStr, con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("添加成功！");
            }
            catch
            {
                MessageBox.Show("输入数据违反要求！");
            }
            finally
            {
                con.Dispose();
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“finalLoginDataSet4.SC”中。您可以根据需要移动或删除它。
            this.sCTableAdapter.Fill(this.finalLoginDataSet4.SC);
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Student_System
{
    public partial class TeaCourse : Form
    {
        public TeaCourse()
        {
            InitializeComponent();
        }

        private void TeaCourse_Load(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);

        }

        private void label3_Click(object sender, EventArgs e)
        {

        }

        private void button5_Click(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);
        }

        private void button1_Click(object sender, EventArgs e)   //增加
        {
            String Cno = textBox1.Text.Trim();
            String Cname = textBox2.Text.Trim();
            String Cpno = textBox3.Text.Trim();
            if (textBox3.Text.Trim() == "")
                Cpno = null;
            String Ccredit = textBox4.Text.Trim();
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
                con.Open();
                string insertStr = "INSERT INTO Course(Cno,Cname,Cpno,Ccredit)   " +
                    "VALUES ('" + Cno + "','" + Cname + "','" + Cpno + "','" + Ccredit + "')";
                SqlCommand cmd = new SqlCommand(insertStr, con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("添加成功！");
            }
            catch
            {
                MessageBox.Show("输入数据违反要求！");
            }
            finally
            {
                con.Dispose();
            }
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);
        }

        private void button2_Click(object sender, EventArgs e)    //删除
        {

            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
            con.Open();
            string select_id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
            //选择的当前行第一列的值，也就是Sno
            string delete_by_id = "delete from Course where Cno=" + select_id;
            //删除语句
            SqlCommand cmd = new SqlCommand(delete_by_id, con);
            cmd.ExecuteNonQuery();
            MessageBox.Show("删除成功！");
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);

          }
            catch
            {
                MessageBox.Show("请选择正确的行！");
            }
            finally
            {
                con.Dispose();

            }
            
           
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);
        }

        private void button6_Click(object sender, EventArgs e)  //完成
        {
            this.Close();
        }

        private void button3_Click(object sender, EventArgs e)   //修改
        {
            String Cno = textBox1.Text.Trim();
            String Cname = textBox2.Text.Trim();
            String Cpno = textBox3.Text.Trim();
            String Ccredit = textBox4.Text.Trim();

            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456");
            try
            {
                con.Open();
                if (Cpno != "")
                {
                    string insertStr = "UPDATE Course SET Cpno='" + Cpno + "' WHERE Cno ='" + Cno + "'";
                    SqlCommand cmd = new SqlCommand(insertStr, con);
                    cmd.ExecuteNonQuery();
                }
                else if (Cname != "")
                {
                    string insertStr = "UPDATE Course SET Cname='" + Cname + "' WHERE Cno ='" + Cno + "'";
                    SqlCommand cmd = new SqlCommand(insertStr, con);
                    cmd.ExecuteNonQuery();
                }
                else if (Ccredit != "")
                {
                    string insertStr = "UPDATE Course SET Ccredit='" + Ccredit + "' WHERE Cno ='" + Cno + "'";
                    SqlCommand cmd = new SqlCommand(insertStr, con);
                    cmd.ExecuteNonQuery();
                }
                MessageBox.Show("修改成功！");
            }
            catch
            {
                MessageBox.Show("输入数据违反要求！");
            }
            finally
            {
                con.Dispose();
            }
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);
        }
         
        private void button4_Click(object sender, EventArgs e)    //查找
        {
            String Cno = textBox1.Text.Trim();
            String Cname = textBox2.Text.Trim();
            String Cpno = textBox3.Text.Trim();
            String Ccredit = textBox4.Text.Trim();
            String select_by_id=null;
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);
            String conn = "Data Source=.;Initial Catalog=FinalLogin;User ID=sa;Password=123456";
            SqlConnection sqlConnection = new SqlConnection(conn);  //实例化连接对象
            try
            {
                
                if (Cpno != "")
                {
                    sqlConnection.Open();
                    select_by_id = "select * from Course where Cpno='" + Cpno + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }
                else if (Cname != "")
                {
                    sqlConnection.Open();
                    select_by_id = "select * from Course where Cname='" + Cname + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }
                    
                else if (Ccredit != "")
                {
                    sqlConnection.Open();
                    select_by_id = "select * from Course where Ccredit='" + Ccredit + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }
               
                else if (Cno != "")
                {
                    sqlConnection.Open();
                    select_by_id = "select * from Course where Cno='" + Cno + "'";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }
               
               else
                {
                    sqlConnection.Open();
                    select_by_id = "select * from Course";
                    SqlCommand cmd = new SqlCommand(select_by_id, sqlConnection);
                    SqlDataReader sqlDataReader = cmd.ExecuteReader();
                    BindingSource bindingSource = new BindingSource();
                    bindingSource.DataSource = sqlDataReader;
                    dataGridView1.DataSource = bindingSource;
                }
               
               
               // sqlDataReader.Close();
                //cmd.ExecuteNonQuery();
                MessageBox.Show("查找成功！");
                
            }
            catch
            {
                MessageBox.Show("查询语句有误，请认真检查SQL语句！");
            }
            finally
            {
                sqlConnection.Dispose();
            }
            // TODO: 这行代码将数据加载到表“finalLoginDataSet6.Course”中。您可以根据需要移动或删除它。
            this.courseTableAdapter.Fill(this.finalLoginDataSet6.Course);
        }
    }
}

上面的是整个系统每个板块的理解，以及总体的功能划分。
说一些知识以外的话，再写简易系统方面，我还是太年轻，昨天我把大概框架写出来之后，我认为基本完成了，今天把一些功能在完善就结束了。是我太低估，细节决定成败这句话了，今天我认为要完成时，运行时，出现各种各样我没见过的错误，我就百度加上问同学，一路磕磕绊绊自我认为写好了，下午开始录视频，这个视频是真真的难录呀，一开始说话总时说一句忘一句，每次大概一分钟，后来说多了，也就开始顺利了，结果录到6-7分钟的时候出现报错，我之后灰溜溜的去改错，然后重新录，再然后录到我倒数第二个功能了，突然出现一个非常小的问题，我想要不一会剪一下，应该没啥大问题，录完之后，视频都没看，就下载了剪辑软件，开始剪辑，等待了一个漫长的导出功能之后，打开视频，天呢，这是什么鬼，为啥大半部分都是黑屏，并没有录完整我的屏幕，百度告诉我你的百分比不对，应该调成100%，然后我操作非常娴熟的开始了新的录制，最后终于录制成功。有些许的艰难，也感觉到老师上网课的艰辛，太累了。
以上就是今天的全部心路历程，感谢观看
附上网页链接：https://www.bilibili.com/video/BV1k5411p7rW