VS2012实现简单登录界面

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 登录x
{
  public partial class Form1 : Form
  {
    public Form1()
    {
      InitializeComponent();
    }

    private void userInfoBindingNavigatorSaveItem_Click(object sender, EventArgs e)
    {
      this.Validate();
      this.userInfoBindingSource.EndEdit();
      this.tableAdapterManager.UpdateAll(this.studentRecordDataSet);

    }

    private void Form1_Load(object sender, EventArgs e)
    {
      // TODO: 这行代码将数据加载到表“studentRecordDataSet1.UserInfo”中。您可以根据需要移动或删除它。
      this.userInfoTableAdapter1.Fill(this.studentRecordDataSet1.UserInfo);
      // TODO: 这行代码将数据加载到表“studentRecordDataSet.UserInfo”中。您可以根据需要移动或删除它。
      this.userInfoTableAdapter.Fill(this.studentRecordDataSet.UserInfo);

    }

    private void passwordLabel_Click(object sender, EventArgs e)
    {

    }

    private void button1_Click(object sender, EventArgs e)
    {
      string connString = @"Data Source=.;Initial Catalog=studentrecord;Integrated Security=True";
      SqlConnection conn = new SqlConnection(connString);
      string sql = "select count(*) from UserInfo where username='" + userNameComboBox.Text + "'and password='" + passwordTextBox.Text + "'";
      conn.Open();
      SqlCommand m = new SqlCommand(sql, conn);
      int num = (int)m.ExecuteScalar();
      if (num > 0)
      {
        Form2 frm2 = new Form2();
        frm2.Show();

      }
      else
      {
        MessageBox.Show("对不起，用户名和密码并不匹配！", "登陆失败");
      }
      conn.Close();
    }

    private void userNameComboBox_SelectedIndexChanged(object sender, EventArgs e)
    {

    }

    private void passwordTextBox_TextChanged(object sender, EventArgs e)
    {

    }
  }
}

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 登录x
{
  public partial class Form2 : Form
  {
    public Form2()
    {
      InitializeComponent();
    }

    private void label1_Click(object sender, EventArgs e)
    {

    }
  }
}