如何写连接字符串中的web.config文件，并从中读取？ [英] How to write connection string in web.config file and read from it?

问题描述

我想写的连接字符串到Web.config中是这样的：

I'm trying to write Connection string to Web.config like this:

<connectionStrings>
  <add name="Dbconnection" connectionString="Server=localhost; 
       Database=OnlineShopping ; Integrated Security=True"/>
</connectionStrings >

和来自像这样写着：

string strcon = 
    ConfigurationManager.ConnectionStrings["Dbconnection"].ConnectionString;
SqlConnection DbConnection = new SqlConnection(strcon);

在运行该程序，我得到因空引用错误。但是当我用这个code：

when run the program I get an error because of the null reference. but when I use this code:

SqlConnection DbConnection = new SqlConnection();
DbConnection.ConnectionString = 
    "Server=localhost; Database=OnlineShopping ; Integrated Security=True";

我没有得到任何错误，程序正常工作！
有什么问题？

I don't get any error and the program works correctly! What is the problem?

推荐答案

添加引用添加 System.Configuration ： -

Add reference to add System.Configuration:-

System.Configuration.ConfigurationManager.
    ConnectionStrings["connectionStringName"].ConnectionString;

你也可以改变WebConfig文件以包括供应商名称： -

Also you can change the WebConfig file to include the provider name:-

    <connectionStrings>
  <add name="Dbconnection" 
       connectionString="Server=localhost; Database=OnlineShopping ; Integrated Security=True" ;
       providerName="System.Data.SqlClient" />
</connectionStrings>

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