学生管理系统1

首先，要了解完成学生管理系统的步骤：

总共有几个模块，我就逐一讲解：

完成登录页面模块：

判断“登录”是否成功的代码：

 1   private void btnLogin_Click(object sender, EventArgs e)
 2         {
 3             string str = DBHelper.str;
 4             SqlConnection con = new SqlConnection(str);
 5             string sql = "select count(1) from student where studentname='" + txtnamea.Text + "' and loginpwd='" + txtpwdtu.Text + "' ";
 6             SqlCommand cmd = new SqlCommand(sql,con);
 7             con.Open();
 8             int count = Convert.ToInt32(cmd.ExecuteScalar());
 9             if (count > 0)
10             {
11                 //MessageBox.Show("登陆成功");
12                 this.Hide();
13                 //Welcome frm = new Welcome();
14               
15                 //frm.name= txtnamea.Text;
16                 //frm.Show();
17             }
18             con.Close();
19             //用户名，密码和登录类型都不能为空
20             if (CheckInput())
21             {
22                 //显示系统管理员主窗体                                          
23                 //隐藏登录窗体
24                 this.Hide();
25             }
26             FrmAdminMain frm = new FrmAdminMain();
27             //方法1：
28             //frm.pwd=txtpwdtu.Text;
29             //方法2:
30             Tool.pwd = txtpwdtu.Text;
31             frm.Show();
32         }

 1  if (this.txtnamea.Text.Trim().Equals(string.Empty))
 2             {
 3                 MessageBox.Show("请输入用户名", caption, MessageBoxButtons.OK, MessageBoxIcon.Information);
 4                 this.txtnamea.Focus();
 5                 return false;
 6             }
 7             else if (this.txtpwdtu.Text.Trim().Equals(string.Empty))
 8             {
 9                 MessageBox.Show("请输入密码", caption, MessageBoxButtons.OK, MessageBoxIcon.Information);
10                 this.txtpwdtu.Focus();
11                 return false;
12             }
13             else if (this.cboLoginType.Text.Trim().Equals(string.Empty))
14             {
15                 MessageBox.Show("请输入登录类型", caption, MessageBoxButtons.OK, MessageBoxIcon.Information);
16                 this.cboLoginType.Focus();
17                 return false;
18             }
19             else
20             {
21                 return true;
22             }

修改密码的窗体：

修改密码的代码：

 1  private void FrmChangePwd_Load(object sender, EventArgs e)
 2         {
 3             //颜色变化
 4             this.BackColor = Color.Red;
 5             //显示旧密码到就文本框里面
 6             txtoldpwd.Text = Tool.pwd;
 7         }
 8 
 9         private void btnqueren_Click(object sender, EventArgs e)
10         {
11             string num = txtnewpwd.Text;
12             string str = DBHelper.str;
13           
14             string sql = "update student set loginpwd='" + num + "' where loginpwd='" + txtoldpwd.Text + "'";
15             SqlConnection con = new SqlConnection(str);
16             SqlCommand cmd = new SqlCommand(sql, con);
17             con.Open();
18             if (txtconfrimpwd.Text.Equals(num))
19             {
20                 int com = Convert.ToInt32(cmd.ExecuteScalar());     
21             }
22           
23             DialogResult result = MessageBox.Show("确定要修改密码吗？","温馨提示",MessageBoxButtons.YesNo,MessageBoxIcon.Question);
24             if (result==DialogResult.Yes)
25             {
26                 this.Close();
27             }
28             con.Close();

制作管理员窗体：

怎样做才使“窗体跳转”的代码：

  //选择"新增学生"时打开"编辑学生信息"窗体
        private void 编辑学生信息ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            FrmEditStudent frm = new FrmEditStudent();
            frm.MdiParent = this;
            frm.Show();
        }

        private void 退出ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DialogResult result = MessageBox.Show("确认要退出吗?", "温馨提示", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
            if (result == DialogResult.Yes)
            {
                this.Close();
            }
        }
        //选择“窗口”中的查询学生时显示的“窗体”
        private void 查询学生信息ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            FrmSearchByName frm = new FrmSearchByName();
            frm.MdiParent = this.MdiParent;
            frm.Show();
        }

        //选择“帮助”中的”关于“时显示的窗体
        private void 关于ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            FrmAbout frm = new FrmAbout();
            frm.MdiParent = this.MdiParent;
            frm.Show();
        }
        private void 修改密码ToolStripMenuItem_Click(object sender, EventArgs e)
        {          
            FrmChangePwd frm = new FrmChangePwd();
            frm.MdiParent = this.MdiParent;
            //让修改密码前，给其pwd赋值
            //frm.pwd = pwd;
            frm.Show();
        }
        private void toolStripDropDownButton1_Click_2(object sender, EventArgs e)
        {
            FrmEditStudent frm = new FrmEditStudent();
            frm.MdiParent = this.MdiParent;
          
            frm.Show();
        }

        private void toolStripDropDownButton2_Click(object sender, EventArgs e)
        {
            FrmSearchByName frm = new FrmSearchByName();
            frm.MdiParent = this.MdiParent;
            frm.Show();

编辑学生窗体：

怎么样才能得到所有“年级名称”的代码：

 1     //加载年级到下拉框信息
 2         public void LoadGrade() {
 3 
 4             //拿到所有年级名称
 5             string str = DBHelper.str;
 6             SqlConnection con = new SqlConnection(str);
 7             string sql = "select gradename from grade";
 8             SqlCommand cmd = new SqlCommand(sql, con);
 9 
10             con.Open();
11             SqlDataReader dr = cmd.ExecuteReader();
12 
13             if (dr != null)
14             {
15                 if (dr.HasRows)
16                 {
17                     while (dr.Read())
18                     {
19                         string gname = dr["gradename"].ToString();
20                         //将年级放到下拉框中
21                         cbograde.Items.Add(gname);
22                     }
23                 }
24             }

拿到所有“学生信息”的代码：

 1   //通过学生学号更改信息
 2         public void LoadStudentbyStudentno() {
 3             string str = DBHelper.str;
 4             SqlConnection con = new SqlConnection(str);
 5          
 6             string sql = "select *from student where studentno=" + studentNo + "";
 7             SqlCommand cmd = new SqlCommand(sql,con);
 8           
 9             try
10             {
11                 con.Open();
12                 SqlDataReader dr = cmd.ExecuteReader();
13                 //一列拆解,复制到当前的文本框
14                 while (dr.Read())
15                 {
16                   //获取名字
17                     string stuname = dr["studentname"].ToString();
18                     txtname.Text = stuname;
19                     //获取电话
20                     string stuphone = dr["phone"].ToString();
21                     txtphone.Text = stuphone;
22                     //获取地址
23                     string stuadress = dr["address"].ToString();
24                     txtadress.Text = stuadress;
25                     //获取邮件
26                     string stuemail= dr["email"].ToString();
27                     txtemail.Text = stuemail;
28                     ////获取密码
29                     //string strpwd=dr["LoginPwd"].ToString();
30                     //txtpwd.Text = strpwd;
31                     ////确认密码
32                     //txttruepwd.Text = strpwd;                               
33                     //获取出生日期
34                     DateTime day =Convert.ToDateTime( dr["birthday"]);
35                     cbobirthdatetime.Value = day;
36                     //获取年级名称
37                     int getid = Convert.ToInt32(dr["gradeid"]);
38                     string gradename = GetidName(getid);
39                     cbograde.Text = gradename;
40                     //获取性别
41                     string genders=dr["gender"].ToString();
42                     if (genders.Equals("0"))
43                     {
44                         rbtnFemale.Checked = true;
45                     }
46                     if(genders.Equals("1")) {
47 
48                         rbtnMale.Checked = true;
49                     }
50                  

将“年级编号”转化为“年级名称”的代码：

 1   //将年级编号转换为年级名称
 2         public string GetidName(int getid)
 3         {
 4             string str = DBHelper.str;
 5             SqlConnection con = new SqlConnection(str);
 6          
 7                string sql = "select gradename from grade where gradeid=" + getid + "";
 8             SqlCommand cmd = new SqlCommand(sql, con);
 9             string getname = "";
10             try
11             {
12                 con.Open();
13                 getname = cmd.ExecuteScalar().ToString();
14             }
15             catch (Exception)
16             {
17 
18             }
19             finally
20             {
21                con.Close();
22             }
23             return getname;

当你点击“修改”的时候，”编辑窗体“变为“修改信息的窗体”的代码：

 1  private void FrmEditStudent_Load(object sender, EventArgs e)
 2         {
 3             LoadGrade();
 4             //当点修改按钮时,变成修改窗体
 5             if (studentNo != 0)
 6             {
 7                 this.Text = "修改学生信息";
 8                 btnsave.Text = "修改";
 9             }
10             else {
11                 this.Text = "编辑学生信息";
12                 btnsave.Text = "保存";          
13             }
14                         
15             txtnano.Text = studentNo.ToString();
16             LoadStudentbyStudentno();
17         }

修改“学生信息”的代码：

 1    public void updateInfo() {
 2             //修改密码
 3             string pwd = txtpwd.Text;
 4             //修改姓名
 5             string studentname = txtname.Text;
 6             //修改性别
 7             string studentgender = string.Empty;
 8             if (rbtnFemale.Checked)//女
 9             {
10                 studentgender = "0";
11             }
12             else if (rbtnMale.Checked)//男
13             {
14                 studentgender = "1";
15             }
16             //如何给下拉框绑定数据
17             int getid = GetIdByName();
18             //修改电话
19             string phone = txtphone.Text;
20             //修改地址
21             string adrers = txtadress.Text;
22             //修改日期
23             DateTime birthdate = this.cbobirthdatetime.Value;
24             //修改邮件
25             string emailt = txtemail.Text;
26             string sql =string.Format("update student set loginpwd='{0}',studentname='{1}',gender='{2}',gradeid='{3}',phone='{4}',address='{5}',birthday='{6}',email='{7}' where studentno={8}", pwd, studentname, studentgender, getid, phone, adrers, birthdate, emailt,studentNo);
27             string str = DBHelper.str;
28             SqlConnection con = new SqlConnection(str);
29             SqlCommand cmd = new SqlCommand(sql, con);
30             con.Open();
31             int count = cmd.ExecuteNonQuery();
32             if (count>0)
33             {
34                 //调用查询窗口的一个DataSelect()方法
35                 frmselectInfo.DataSelect();
36                 MessageBox.Show("修改成功");
37             }
38             else
39             {
40                 MessageBox.Show("失败");
41             }

 1 //根据学号是否为0，判定该按钮用来执行“添加”还是“修改”
 2             if (studentNo != 0)
 3             {
 4                 //修改
 5                 updateInfo();
 6             }
 7             else
 8             {
 9                 //添加
10                 AddStudent();
11             }

将“年级名称”变为“年级名称”的代码：

 1   //该方法将年级名称转换成年级编号
 2         public int GetIdByName()
 3         {
 4             string str = DBHelper.str;
 5             SqlConnection con = new SqlConnection(str);
 6             string sql = "select gradeid from grade where gradename='" + cbograde.Text + "'";
 7             SqlCommand cmd = new SqlCommand(sql, con);
 8             int getid = 0;
 9             try
10             {
11                 con.Open();
12                 getid = Convert.ToInt32(cmd.ExecuteScalar());
13             }

按姓名查询学生信息的窗体：

查询和在Load事件中提前显示的代码：

 1     private void FrmSearchByName_Load(object sender, EventArgs e)
 2         {
 3             //在Load事件中编写代码提前显示
 4             //查询
 5             string sql = @"select Studentno,Studentname,Gender,gradename
 6                             from student,grade
 7                             where student.gradeid=grade.gradeid ";
 8             LoadFrmListView(sql);
 9         }
10         //查询数据
11         public void DataSelect()
12         {
13             lvlistview.Items.Clear();
14             string sql = @"select studentno,studentname,Gender,gradename from student,grade   
15            where student.gradeid=grade.gradeid and studentname like '%" + txtsearchname.Text + "%'";
16             LoadFrmListView(sql);
17         }

获取学号的代码：

 1   private void 修改ToolStripMenuItem_Click(object sender, EventArgs e)
 2         {
 3 
 4             if (this.lvlistview.SelectedItems.Count > 0)
 5             {
 6                 FrmEditStudent frm = new FrmEditStudent();
 7                 //将选中的学号传递到"编辑学生信息窗体"
 8                 //frm.studentNo = Convert.ToInt32(this.lvlistview.SelectedItems[0].Text);也可以
 9                 frm.studentNo = Convert.ToInt32(this.lvlistview.SelectedItems[0].SubItems[0].Text);
10                 frm.MdiParent = this.MdiParent;
11                 frm.frmselectInfo = this;
12                 frm.Show();

获取学生信息的代码：：

 1    //获取学号
 2                             int stuNo = Convert.ToInt32(dr["studentno"]);
 3                             //第二列获取姓名 stuname
 4                             string stuName = Convert.ToString(dr["studentname"]);
 5                             //第三列 获取 性别
 6                             string stugender = Convert.ToString(dr["gender"]);
 7                             //获取年级名称
 8                             string gname = Convert.ToString(dr["gradename"]);
 9                             //
10                             ListViewItem lvItem = new ListViewItem(stuNo.ToString());
11                             lvItem.SubItems.Add(stuName);//接收学生名字
12                             lvItem.SubItems.Add(stugender);//接收学生性别
13                             lvItem.SubItems.Add(gname);//接收学生年级名称
14                             //让lvItem和ListView关联
15                             lvlistview.Items.Add(lvItem);
16                         }

关于我们的窗体：

计时器的Tick事件处理方法，定时变换图片框中的图片代码：

 1  private void timetime_Tick(object sender, EventArgs e)
 2         {
 3             //如果当前显示的图片索引没有到最大值就继续增加
 4             if (index < imglist.Images.Count - 1)
 5             {
 6                 index++;
 7             }
 8             else {
 9                 index = 0;
10             }
11             //设置图片框显示的图片
12             this.pictureBox1.Image = imglist.Images[index];

按年级查询学生信息的的窗体：

加载年级的代码：

 1   //加载年级信息
 2         public void LoadGradeInfo() {
 3 
 4             //创建数据库连接
 5             string str = DBHelper.str;
 6             SqlConnection con = new SqlConnection(str);
 7             //string sql = "select studentno,studentname,gender,birthday from student";    
 8             string sql = "select gradeid,gradename from Grade";
 9             SqlDataAdapter da = new SqlDataAdapter(sql, con);
10             DataSet ds = new DataSet();
11             da.Fill(ds,"Grade");
12             DataRow row =ds.Tables["Grade"].NewRow();
13             row[0]=-1;
14             row[1] = "全部";
15             ds.Tables["Grade"].Rows.InsertAt(row,0);
16            
17             cbograde.DataSource = ds.Tables["Grade"];
18             //ValueMember下拉框显示的隐藏值
19             cbograde.ValueMember = "gradeid";
20             //DisplayMember下拉框显示的真实值
21             cbograde.DisplayMember = "Gradename";
22             cbograde.SelectedIndex = 0;                                                                                                                                                                                                                                                                                                     
23         }   

修改的代码：

 1  //保存修改
 2         private void btnSAve_Click(object sender, EventArgs e)
 3         {
 4             DialogResult result = MessageBox.Show("确定要修改吗？",caption,MessageBoxButtons.YesNo,MessageBoxIcon.Question);
 5             if (result==DialogResult.Yes)//确认保存修改
 6             {
 7                 //使用SqlCommandBuilder构建增删改的command操作
 8                 SqlCommandBuilder sq = new SqlCommandBuilder(da);
 9                 //将数据集中student表的数据交给数据库更新
10                 da.Update(ds, "student");
11             }

删除信息的窗体：

获取信息代码：

 1  public void FillTables(){
 2            string str = DBHelper.str;
 3            //取消英文列自动生成,就是没写列名称时，不能用英文列代替
 4            dgstudenlist.AutoGenerateColumns = false;
 5            SqlConnection con = new SqlConnection(str);
 6            string sql = "select studentno,studentname,gender,gradename,phone from student,grade where student.gradeid=grade.gradeid";
 7            SqlDataAdapter da = new SqlDataAdapter(sql, con);
 8            DataSet ds = new DataSet();
 9            da.Fill(ds, "student");
10            this.dgstudenlist.DataSource = ds.Tables["student"]; 
11         }
12         private void FrmStudentList_Load(object sender, EventArgs e)
13         {
14             FillTables();
15         }

删除操作的代码：

 1    //确认删除操作
 2                 DialogResult result = MessageBox.Show("确认删除改学生吗？同时会删除该学生的成绩！！！", "提示", MessageBoxButtons.YesNo, MessageBoxIcon.Warning);
 3                 if (result == DialogResult.Yes)
 4                 {
 5                     if (dgstudenlist.SelectedRows.Count > 0)
 6                     {
 7                         //获得选中的学生的学号
 8                         int studentno = Convert.ToInt32(dgstudenlist.SelectedRows[0].Cells["studentno"].Value);
 9                     }
10                     string str = DBHelper.str;
11                     SqlConnection con = new SqlConnection(str);
12                     string sql = string.Format("delete from result where studentno={0}", StudentNO);
13                     con.Open();
14                     SqlCommand cmd = new SqlCommand(sql, con);
15                     int count = cmd.ExecuteNonQuery();
16                     //删除学生信息
17                     sql = string.Format("delete from student where studentno={0}", StudentNO);
18                     cmd.CommandText = sql;
19                     int result1 = cmd.ExecuteNonQuery();
20                     if (result1 == 1)
21                     {
22                         MessageBox.Show("删除成公！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
23                         //重新查询数据，绑定数据源，重新帅选
24                         FillTables();
25                     }
26                     con.Close();

其中一些重要代码： 

1.向数据集年级表的第一行添加数据“全部”或者“请选择”的代码:

 1 1    DataRow row = ds.Tables["Grade"].NewRow();//形成行对象
 2  2             row["gradeid"] = -1;//给该行的列赋值 
 3  3             row["gradename"] = "全部";
 4  4             ds.Tables["Grade"].Rows.InsertAt(row, 0);//行对象和Table产生关系
 5  5 
 6  6 
 7  7 或者
 8  8 
 9  9        //01.形成行对象   table.NewRow()
10 10             DataTable table = ds.Tables[0];
11 11             DataRow dr=table.NewRow();
12 12             //02.给该行的列赋值 dr[0]=-1;  
13 13             dr[0] = -1;
14 14             dr[1] = "请选择";
15 15            //03.让行对象和Table产生关系table.Rows.InsertAt()
16 16             table.Rows.InsertAt(dr,0);

2.向下拉框赋值，即年级名称，隐藏年级编号:

 1       SqlDataAdapter da = new SqlDataAdapter(sql, con);
 2             DataSet ds = new DataSet();
 3             da.Fill(ds, "Grade");   
 4       cbograde.DataSource = ds.Tables["Grade"];
 5             //ValueMember下拉框显示的隐藏值gradeid
 6             cbograde.ValueMember = "gradeid";
 7             //DisplayMember下拉框显示的真实值Gradename
 8             cbograde.DisplayMember = "Gradename";
 9             cbograde.SelectedIndex = 0;        //索引为0
10             con.Close();