private void btnOK_Click(object sender, System.EventArgs e)
  {
   string strConn = "server=192.168.0.51;database=chengheng;User id=sa; password=123";
   if(texName.Text.Trim()=="")
   {
    this.RegisterStartupScript("sf","<script language='javascript'>alert('用户名不能为空');document.all('texName').focus()</script>");
    return;
   }
   else if(texPassword.Text.Trim()=="")
   {
    this.RegisterStartupScript("sfs","<script language='javascript'>alert('密码不能为空');document.all('texPassword').focus()</script>");
    return;
   }
   else
   {
    //将获取的密码加密与数据库中加了密的密码相比较
    byte[] by = md5.ComputeHash(utf.GetBytes(texPassword.Text.Trim()));
    string resultPass = System.Text.UTF8Encoding.Unicode.GetString(by);
    conn.ConnectionString=strConn;
    SqlCommand comm = new SqlCommand();
    string name = texName.Text.Trim().ToString();
    comm.CommandText="select Ruser_pwd,Ruser_nm from Ruser where Accountno = @name";
    comm.Parameters.Add("@name",SqlDbType.NVarChar,40);
    comm.Parameters["@name"].Value=name;
    try
    {    
     conn.Open();
     comm.Connection=conn;
     SqlDataReader dr=comm.ExecuteReader();
     if(dr.Read())
     {
      //用户存在，对密码进行检查
      if(dr.GetValue(0).Equals(resultPass))
      {
       string user_name=dr.GetValue(1).ToString();
       string user_Accountno=texName.Text.Trim();
       Session["logon_name"]=user_name;
       Session["logon_Accountno"]=user_Accountno;
       //登录成功，进行页面导向

      }
      else
      {
       this.RegisterStartupScript("wp","<script language='javascript'>alert('密码错误，请检查。')</script>");
      }
      
     }
     else
     {
      this.RegisterStartupScript("nu","<script language=javascript>alert('用户名不存在，请检查。')</script>");
     }
    }
    catch(Exception exec)
    {  
     this.RegisterStartupScript("wc","<script language=javascript>alert('网络连接有异，请稍后重试。')</script>");
    }  
    finally
    {
     conn.Close();
    }
   }
  }