新手写一段学员信息管理系统，有代码冗余的情况请谅解，代码如下，请大神指点

//登陆入口页面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 学员管理系统{ public partial class Lo : Form { public Lo() { InitializeComponent(); } string sql= "Data Source=LAPTOP-PCMBBB0N;Initial Catalog=DB_Student;Trusted_Connection=true;"; private void Log_Load(object sender, EventArgs e) { this.FormBorderStyle = FormBorderStyle.FixedToolWindow; this.Location = new Point(Screen.PrimaryScreen.Bounds.Width / 2 - this.Width / 2, Screen.PrimaryScreen.Bounds.Height / 2 - this.Height / 2); } Main main; private void button1_Click(object sender, EventArgs e) { try { string pwd =txtpwd.Text; if (pwd.ToString() == "") { label2.Visible = true; label2.Text = "密码不能为空！"; } else { if (pwd.Equals((table.Rows[0]["Pwd"]).ToString())) { label2.Visible = false; main = new Main(); main.Show(); this.Visible = false; } else { label2.Text = "密码不正确！"; label2.Visible = true; } } } catch (Exception) { throw; } } DataTable table = new DataTable(); private void txtid_Leave(object sender, EventArgs e) { try { int id = int.Parse(txtid.Text); //1.链接数据库对象 SqlConnection sqlcon = new SqlConnection(sql); //3.创建数据库命令对象 SqlCommand cmd = new SqlCommand(); cmd.Connection = sqlcon; cmd.CommandText = "SELECT * FROM Student WHERE ID=" + id; //5.数据适配器对象 SqlDataAdapter sda = new SqlDataAdapter(); sda.SelectCommand = cmd; //6.这个table可以用来接受适配的最终结果 sda.Fill(table); if (table.Rows.Count > 0) { label1.Visible = false; } else { label1.Visible = true; label1.Text = "输入ID不存在！"; } } catch (Exception) { label1.Visible = true; label1.Text = "请输入纯数字ID！"; txtid.Focus(); txtid.Text = ""; } } private void button2_Click_1(object sender, EventArgs e) { Register register = new Register(); register.ShowDialog(); this.Visible = true; label1.Visible = false; } }}

//注册页面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 System.Data.SqlClient;namespace 学员管理系统{ public partial class Register : Form { public Register() { InitializeComponent(); } string sql = "Data Source=LAPTOP-PCMBBB0N;Initial Catalog=DB_Student;Trusted_Connection=true;"; private void button1_Click(object sender, EventArgs e) { try { SqlConnection sqlCon = new SqlConnection(sql); string sqltxt = string.Format("INSERT INTO Student VALUES('{0}','{1}','{2}','{3}','{4}')", textBox2.Text, textBox1.Text, textBox3.Text, textBox4.Text, textBox5.Text); SqlCommand cmd = new SqlCommand(sqltxt, sqlCon); sqlCon.Open(); int res = cmd.ExecuteNonQuery(); if (res > 0) { MessageBox.Show("注册成功"); textBox1.Text = ""; textBox2.Text = ""; textBox3.Text = ""; textBox4.Text = ""; textBox5.Text = ""; textBox1.Focus(); } } catch (Exception) { throw; } }//信息页面（可以进行数据库信息更改，删除，查看 以及翻页操作）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 System.Data.SqlClient;namespace 学员管理系统{ public partial class Main : Form { public Main() { InitializeComponent(); } string strcon = "Data Source=LAPTOP-PCMBBB0N;Initial Catalog=DB_Student;Trusted_Connection=true;"; int countPage; int nowPage = 1; SqlConnection sqlCon; private void Main_Load(object sender, EventArgs e) { sqlCon = new SqlConnection(strcon); //绑定页码信息 try { string sql = "SELECT COUNT(*) FROM Student"; SqlCommand cmdl = new SqlCommand(sql, sqlCon); sqlCon.Open(); object res = cmdl.ExecuteScalar(); if (res != null) { if ((int)res % 6 > 0) { countPage = ((int)res / 6) + 1; } else { countPage = (int)res / 6; } } } catch (Exception) { throw; } finally { sqlCon.Close(); } //初始信息绑定 try { SetPage(sqlCon); dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill; dataGridView1.RowHeadersVisible = false; foreach (DataGridViewColumn dc in dataGridView1.Columns) { dc.SortMode = DataGridViewColumnSortMode.Programmatic; } dataGridView1.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter; dataGridView1.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter; dataGridView1.ScrollBars = ScrollBars.None; dataGridView1.MultiSelect = false; dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect; dataGridView1.AllowUserToResizeRows = false; dataGridView1.AllowUserToResizeColumns = false; dataGridView1.ScrollBars = ScrollBars.None; dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill; dataGridView1.AllowUserToAddRows = false; dataGridView1.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter; dataGridView1.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter; foreach (DataGridViewColumn item in dataGridView1.Columns) { item.SortMode = DataGridViewColumnSortMode.NotSortable; } dataGridView1.ReadOnly = true; dataGridView1.CellMouseDown += DataGridView1_CellMouseDown; } catch (Exception ex) { throw; } finally { sqlCon.Close(); } } private void SetPage(SqlConnection sqlCon) { string sql = string.Format("SELECT ID AS '账号',NAME AS '姓名',Sex AS '性别',Age AS '年龄',Zhanli AS '电话' FROM Student WHERE ID IN(SELECT TOP(6) ID FROM Student WHERE ID NOT IN (SELECT TOP({0}) ID FROM Student ORDER BY ID)ORDER BY ID ) ORDER BY ID", (nowPage - 1) * 6); SqlCommand cmd = new SqlCommand(sql, sqlCon); SqlDataAdapter sda = new SqlDataAdapter(cmd); DataSet ds = new DataSet(); sda.Fill(ds); dataGridView1.DataSource = ds.Tables[0]; label1.Text = nowPage.ToString(); label3.Text = countPage.ToString(); } private void DataGridView1_CellMouseDown(object sender, DataGridViewCellMouseEventArgs e) { if (e.Button == MouseButtons.Right && dataGridView1.SelectedRows.Count > 0) { dataGridView1.ClearSelection(); dataGridView1.Rows[e.RowIndex].Selected = true; ID.Idd = (int)dataGridView1.SelectedCells[0].Value; contextMenuStrip1.Show(); } } private void 删除ToolStripMenuItem1_Click(object sender, EventArgs e) { try { SqlConnection sqlCon = new SqlConnection(strcon); string sqltxt = "DELETE FROM Student WHERE ID=" + ID.Idd; SqlCommand cmd = new SqlCommand(sqltxt, sqlCon); sqlCon.Open(); int res = cmd.ExecuteNonQuery(); if (res > 0) { MessageBox.Show("删除成功！"); Main ma = new 学员管理系统.Main(); ma.Show(); this.Visible = false; } } catch (Exception) { throw; } } private void 修改密码ToolStripMenuItem_Click(object sender, EventArgs e) { xiugai xiu = new xiugai(); xiu.ShowDialog(); this.Visible = false; } private void 查看详细信息ToolStripMenuItem_Click(object sender, EventArgs e) { chakan cha = new chakan(); cha.ShowDialog(); this.Visible = false; } private void 下一页ToolStripMenuItem_Click(object sender, EventArgs e) { if (nowPage >= countPage) { return; } else { nowPage++; SetPage(sqlCon); } } private void 上一页ToolStripMenuItem_Click(object sender, EventArgs e) { if (nowPage <= 1) { return; } else { nowPage--; SetPage(sqlCon); } } }}/查看详细信息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 学员管理系统{ public partial class chakan : Form { public chakan() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { Main ma = new 学员管理系统.Main(); ma.Show(); this.Visible = false; } string sql = "Data Source=LAPTOP-PCMBBB0N;Initial Catalog=DB_Student;Trusted_Connection=true;"; private void chakan_Load(object sender, EventArgs e) { try { SqlConnection sqlcon = new SqlConnection(sql); string sqltxt = "SELECT * FROM Student WHERE ID="+ID.Idd; SqlCommand cmd = new SqlCommand(sqltxt, sqlcon); sqlcon.Open(); SqlDataAdapter sda = new SqlDataAdapter(cmd); DataTable table = new DataTable(); sda.Fill(table); Name1.Text = (table.Rows[0]["NAME"]).ToString(); ID1.Text = (table.Rows[0]["ID"]).ToString(); Pwd.Text = (table.Rows[0]["Pwd"]).ToString(); Sex.Text = (table.Rows[0]["Sex"]).ToString(); Age.Text = (table.Rows[0]["Age"]).ToString(); Zhanli.Text = (table.Rows[0]["Zhanli"]).ToString(); } catch (Exception) { throw; } } }}//创建一个类用来存储用户账号using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace 学员管理系统{ public class ID { public static int idd; public static int Idd { get { return idd; } set { idd = value; } } }}//修改密码using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;using System.Data.SqlClient;namespace 学员管理系统{ public partial class xiugai : Form { public xiugai() { InitializeComponent(); } string sql = "Data Source=LAPTOP-PCMBBB0N;Initial Catalog=DB_Student;Trusted_Connection=true;"; private void button1_Click(object sender, EventArgs e) { string yuan = textBox1.Text; string New = textBox2.Text; string New2 = textBox3.Text; if (yuan=="") { label4.Visible = true; textBox1.Focus(); } else { if (New=="") { label5.Visible = true; textBox2.Focus(); } else { if (New2==""||New2!=New) { label6.Visible = true; textBox3.Focus(); } else { try { int num = int.Parse(yuan); SqlConnection sqlcon = new SqlConnection(sql); string sqltext = "UPDATE Student SET Pwd=" + New2 + "WHERE ID="+ID.Idd; //string sqltext = "UPDATE StudentInfor SET Pwd=" + New2 + "WHERE ID="+ID.Idd; SqlCommand cmd = new SqlCommand(sqltext,sqlcon); sqlcon.Open(); int res = cmd.ExecuteNonQuery(); if (res>0) { MessageBox.Show("修改成功"); } } catch (Exception) { throw; } } } } } }}

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