C＃SqlCommand Connection.Open（）問題

Question

我有一個C＃ASP.NET Web應用程序，我正在嘗試使用數據庫表中的列填充ASP：DropDownList。

我的代碼：

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Web.Configuration;

namespace CRM2Sage
{
    public partial class SOPOrderEntry : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Fill1();
        }

        public void Fill1()
        {
            SqlCommand cmd = new SqlCommand("SELECT * FROM Products", new SqlConnection(WebConfigurationManager.AppSettings["CRM2Sage"]));
            //cmd.Connection.Open();
            cmd.Connection.Open();

            SqlDataReader ddlValues;
            ddlValues = cmd.ExecuteReader();

            vproduct.DataSource = ddlValues;
            vproduct.DataValueField = "theName";
            vproduct.DataTextField = "theName";
            vproduct.DataBind();

            cmd.Connection.Close();
            cmd.Connection.Dispose();
        }
    }
}

當我運行頁面時，我收到以下錯誤

ConnectionString屬性尚未初始化。

指向cmd.Connection.Open(); 我無法理解為什么，SQL連接存儲在我的web.config文件中。

web.config

<?xml version="1.0"?>
<configuration>

    <appSettings />
    <connectionStrings>
      <add name="CRM2Sage" connectionString="Data Source=W2003CRMDEMO; Initial Catalog=CRM2Sage; User ID=newSA; Password=password;" providerName="System.Data.SqlClient" />
    </connectionStrings>

    <system.web>
        <compilation debug="true">

        </compilation>
        <!--
            The <authentication> section enables configuration 
            of the security authentication mode used by 
            ASP.NET to identify an incoming user. 
        -->
        <authentication mode="Windows" />
        <!--
            The <customErrors> section enables configuration 
            of what to do if/when an unhandled error occurs 
            during the execution of a request. Specifically, 
            it enables developers to configure html error pages 
            to be displayed in place of a error stack trace.

        <customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm">
            <error statusCode="403" redirect="NoAccess.htm" />
            <error statusCode="404" redirect="FileNotFound.htm" />
        </customErrors>
        -->
    </system.web>
</configuration>

有人可以幫忙嗎？

干杯

賈斯汀

Answer 1

您需要檢索.ConnectionString屬性：

string connectionString = WebConfigurationManager.ConnectionStrings["CRM2Sage"].ConnectionString;

using(SqlConnection _con = new SqlConnection(connectionString))
using(SqlCommand cmd = new SqlCommand("SELECT * FROM Products", _con))
{
   // do your stuff here
}

你現在正在做的只是通過CRM2Sage的名稱檢索<connectionStrings>下的整個條目。

Answer 2

問題是，您正在訪問AppSettings ，但是您想要訪問連接字符串：

new SqlConnection(WebConfigurationManager.ConnectionStrings.ConnectionStrings["CRM2Sage"].ConnectionString)

Answer 3

您可以使用

System.Web.Configuration.WebConfigurationManager.ConnectionStrings["CRM2Sage"].ConnectionString;

Or
System.Configuration.ConfigurationManager.ConnectionStrings["CRM2Sage"].ConnectionString;

在asp.net中。 但不是

WebConfigurationManager.AppSettings["CRM2Sage"]