用VS2008调试运行，没调试之前已经连接到了数据库。然后我就点调试 打开网页 输入账户密码啥的，然后点登陆 就出现了
“alert('在建立与服务器的连接时出错。在连接到 SQL Server 2005 时，在默认的设置下 SQL Server 不允许进行远程连接可能会导致此失败。 (provider: 命名管道提供程序, error: 40 - 无法打开到 SQL Server 的连接)') ”
这个错误，那个大大帮帮忙，看下为什么？不胜感激

没调试之前已经连接到了数据库？ 那是怎么连接的？ 是用vs自带的数据库连接么 windows验证 还是sqlserver混合验证？  
报错可能连接字符串有问题吧 原因很多的 要看具体情况

我安装的是SQL2005 然后用VS2008上面的工具--连接到数据库 连接的数据库

下面是代码，看下应该怎么修改




using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public partial class LoginLibrary : System.Web.UI.Page
{

    private string connString = ConfigurationManager.ConnectionStrings["LibraryConnectionString"].ToString();
    private SqlConnection sqlCon;
    private SqlDataReader sqlDa;



    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["UserName"] == null || Session["UserName"].ToString() == "")
        {
            txtName.Focus();
        }
        else
        {
            Response.Redirect("LoginManage/LoginOk.aspx");
        }
    }



    protected void imgCancel_Click(object sender, ImageClickEventArgs e)
    {
        Response.Write("<script>window.close();</script>");
    }
    protected void imgSubmit_Click(object sender, ImageClickEventArgs e)
    {
        try
        {
            sqlCon = new SqlConnection(connString);
            if (sqlCon.State == ConnectionState.Closed)
            {
                sqlCon.Open();
            }
            SqlCommand sqlCmd = new SqlCommand();
            sqlCmd.Connection = sqlCon;
             = "Select * from tb_admin Where username='" + txtName.Text.Trim() + "'";
            sqlDa = sqlCmd.ExecuteReader();
            if (Session["UserName"] == null || Session["UserName"].ToString() == "")
            {
                if (sqlDa.HasRows)
                {
                    while (sqlDa.Read())
                    {
                        if (txtPwd.Text.Trim() == sqlDa["password"].ToString().Trim() && txtCode.Text.ToLower() == Session["CheckCode"].ToString()&&txtName.Text.Trim()=="admin")
                        {
                            //Session["User"] = dr.GetValue(0)
                            Session["UserName"] = txtName.Text.Trim();
                            FormsAuthentication.RedirectFromLoginPage(txtName.Text, false);
                            FormsAuthentication.SetAuthCookie(txtName.Text, false);
                            Response.Redirect("Default.aspx");
                        }
                        else if(txtPwd.Text.Trim() == sqlDa["password"].ToString().Trim() && txtCode.Text.ToLower() == Session["CheckCode"].ToString())
                        {
                            Session["UserName"] = txtName.Text.Trim();
                            FormsAuthentication.RedirectFromLoginPage(txtName.Text, false);
                            FormsAuthentication.SetAuthCookie(txtName.Text, false);
                            Response.Redirect("User/Default.aspx");
                        }
                        else if (txtPwd.Text.Trim() != sqlDa["password"].ToString())
                        {
                            Response.Write("<script>alert('密码输入错误！')</script>");
                        }
                        else if (txtCode.Text.ToLower() != Session["CheckCode"].ToString())
                        {
                            Response.Write("<script>alert('验证码输入错误!')</script>");
                        }
                    }
                }
                else
                {
                    Response.Write("<script>alert('非法登录,没有此用户!')</script>");
                }
            }
            else
            {
                Response.Redirect("LoginManage/LoginOk.aspx");
            }
        }

        catch (SqlException ex)
        {
            Response.Write("<scrip>alert('"+ex.Message+"')</script>");
        }
        finally
        {
            if (sqlCon.State == ConnectionState.Open)
            {
                sqlCon.Close();
            }
        }
    }
}

求解答。。自己顶

设个断点，看看你的private string connString = ConfigurationManager.ConnectionStrings["LibraryConnectionString"].ToString();
是不是正确，然后

 SqlCommand sqlCmd = new SqlCommand();
            sqlCmd.Connection = sqlCon;
             = "Select * from tb_admin Where username='" + txtName.Text.Trim() + "'";
            sqlDa = sqlCmd.ExecuteReader();
            if (Session["UserName"] == null || Session["UserName"].ToString() == "")
            {
                if (sqlDa.HasRows) //设个断点，看看返回值是true还是false
                {
                    while (sqlDa.Read())