Question

string str = ConfigurationManager.ConnectionStrings["MySchool"].ConnectionString;未引用对象的实例

connectionString.xml文件如下：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionstrings>
<add name="DataBaseOwner" connectionString="dbo"/>
<add name="MySchool" connectionString="Data Source=.;Initial Catalog=MySchool;Integrated Security=True"/>
</connectionstrings>
</configuration>
调用如下：
private readonly string constr = ConfigurationManager.ConnectionStrings["MySchool"].ConnectionString;未将对象引用设置到对象的实例
我引用了using System.Configuration；

Answer 1

你的内容，必须放在 web.config 或者 app.config 里面， 而不是放在 connectionString.xml

Answer 2

这样试一下。

private readonly string constr=(@ConfigurationSettings.AppSettings["MySchool"]);