c#登录代码

这篇博客展示了如何在C#中实现一个简单的登录功能。通过获取输入的用户名和密码,连接到SQL数据库进行验证。如果匹配成功,将显示新的检查页面;否则,显示错误提示。

private void btnLogin_Click(object sender, System.EventArgs e)
  {
   string userID=this.txtUserID.Text;
   string pwd =this.txtPwd.Text;
   SqlConnection conn=new SqlConnection("data source=(local);user id=sa;pwd=;initial catalog=test;integrated security=SSPI");
   conn.Open();
   SqlCommand cmd=new SqlCommand("select count(*) as flag from login where userID="+"'"+userID+"'"+"and pwd ="+"'"+pwd+"'",conn);
   cmd.ExecuteNonQuery();
   int flag=Convert.ToInt32(cmd.ExecuteScalar().ToString());
               
   if(flag>0)
   {
    Form check=new check();
    check.Show();
    this.Hide();
   }
   else
   {
    this.label3.Enabled=true;
    this.label3.Text="出错";
    this.label3.Visible=true;
   }

  
  }

C#编程登陆界面代码 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Data.OleDb; namespace 人事管理系统 { public partial class FormLogin : Form { public FormLogin() { InitializeComponent(); } private void FormLogin_Load(object sender, EventArgs e) { } public void buttonLogin_Click_1(object sender, EventArgs e) { try { if (textBoxName .Text =="") { MessageBox.Show ("用户名不能为空!","提示",MessageBoxButtons.OKCancel,MessageBoxIcon.Warning ); } else { if (textBoxPassword .Text =="") { MessageBox.Show("密码不能为空!", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Warning); } else { String connStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Application.StartupPath + "\\人事数据库.mdb"; OleDbConnection conn = new OleDbConnection(connStr); //String sql = "select count(*) from 用户密码表 where username='" + textBoxName.Text + "' and password='" + textBoxPassword.Text + "'"; conn.Open(); string sql = "select count(*) from 用户密码表 where username=@name and password=@pass"; OleDbCommand cmd = new OleDbCommand(sql ,conn ); cmd.Parameters.Add(new OleDbParameter ("@name",OleDbType .Char )); cmd.Parameters["@name"].Value = textBoxName.Text; cmd.Parameters.Add(new OleDbParameter("@pass", OleDbType.Char)); cmd.Parameters["@pass"].Value = textBoxPassword.Text; //OleDbDataAdapter da = new OleDbDataAdapter(sql, conn); //DataTable dt = new DataTable(); //da.Fill(dt); //int i = dt.Rows.Count; int i =(int )cmd.ExecuteScalar (); conn.Close(); if (i > 0) { FormMain fm = new FormMain(); fm.admintime = DateTime.Now.ToShortDateString(); fm.adminname = textBoxName.Text; fm.Show(); this.Hide (); } else { MessageBox.Show("用户名或密码错误!", "提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Error ); { textBoxName.Text = ""; textBoxPassword.Text = ""; textBoxName.Focus(); } } } } } catch (Exception ex) { MessageBox.Show(ex.ToString()); } } private void button1_Click(object sender, EventArgs e) { if (MessageBox.Show("您确定要退出本系统吗?", "警告", MessageBoxButtons.OKCancel, MessageBoxIcon.Warning) == DialogResult.OK) { Application.Exit(); } } private void textBoxName_KeyPress(object sender, KeyPressEventArgs e) { if (e.KeyChar == 13) { textBoxPassword.Focus(); e.Handled = true; } } private void textBoxPassword_KeyPress(object sender, KeyPressEventArgs e) { if (e.KeyChar == 13) { buttonLogin.Focus(); e.Handled = true; } } private void linkLabeladd_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e) { Form添加 fpty = new Form添加(); fpty.Show(); } private void linkLabelpass_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e) { Formpasswordmodify fpmd = new Formpasswordmodify(); fpmd.Show(); } } }
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