C#怎样实现登录框功能？

Question

http://expert.csdn.net/Expert/topic/1957/1957958.xml?temp=.7107202

Answer 1

可能使这样的吧：//User,UID,UPWS,JB是全局string变量
//t_uid,t_upws是登陆框的用户名和密码文本框
string s_uid=t_uid.Text.Trim();
string s_upws=t_upws.Text.Trim();
string connStr="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=路径\aa.mdb";
OleDbConnection conn=new OleDbConnection(connStr);
conn.Open();
string strSql="select * from User where UID='"&s_uid&"' and UPWS='"&s_upws&"'";
OleDbCommand cmd = new OleDbCommand(strSql,conn);
OleDbDataReader reader1=cmd.ExecuteReader();
if(reader1.Read())                   //登陆成功
{                      
  User=s_uid;
  UPWS=s_upws;
  JB=reader1["JB"].ToString();
  reader1.close();
  conn.close();
  关闭登陆窗口进入主窗口；
}
else
  MessageBox("用户不存在或者密码不正确请重新输入！");

Answer 2

private void button1_Click(object sender, System.EventArgs e)
{
string sql="SELECT * FROM adminguanli";
string pw=null;
try
{
thisConnection.Open(); SqlCommand thisCommand=thisConnection.CreateCommand();
thisCommand.CommandText=sql; SqlDataReader thisReader=thisCommand.ExecuteReader(); while(thisReader.Read())
{
pw=thisReader["adminpass"].ToString().Trim();
} thisReader.Close();
thisConnection.Close(); if(textBox1.Text=="")
{
MessageBox.Show("请输入密码！");
textBox1.Focus();
}
else
{
if(pw==textBox1.Text)
{
panel1.Visible=true;
button3.Focus();
}
else
{
MessageBox.Show("您输入的密码不正确，请重新输入！");
textBox1.Text=null;
}
}
}
catch
{
} }