我猜您需要添加一个对系统的引用。配置程序集(如果尚未添加)。

此外，您可能需要在代码文件的顶部插入以下行:

using System.Configuration;

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.DataVisualization.Charting;
using System.Web.UI.WebControls;  

c#

string constring = ConfigurationManager.ConnectionStrings["ABCD"].ConnectionString;
                using (SqlConnection con = new SqlConnection(constring))

下面的网站。配置文件代码

<connectionStrings>
    <add name="ABCD" connectionString="Data Source=DESKTOP-SU3NKUU\MSSQLSERVER2016;Initial Catalog=TESTKISWRMIP;Integrated Security=True" providerName="System.Data.SqlClient"/>
  </connectionStrings>

在上面的代码中，ABCD是连接名称

using System.Configuration;


string conn = ConfigurationManager.ConnectionStrings["ConStringName"].ToString();

首先加上这个:

using System.Configuration;

C#

// Add a using directive at the top of your code file    
using System.Configuration;

// Within the code body set your variable    
string cs = ConfigurationManager.ConnectionStrings["connectionStringName"].ConnectionString;

VB

' Add an Imports statement at the top of your code file    
Imports System.Configuration

' Within the code body set your variable    
Dim cs as String = ConfigurationManager.ConnectionStrings("connectionStringName").ConnectionString

添加系统。配置作为参考。

由于一些奇怪的原因，默认情况下它不包括在内。