C# 全局元素'；配置'；已申报；2012年WPF

这是我的App.coonfig

  <?xml version="1.0" encoding="utf-8" ?>
    <configuration>
        <startup> 
            <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
        </startup>
      <connectionstrings>
        <add connectionstring="Data Source=YourDataSource; User Id=YourUserName;Password=YourPassword; Initial Catalog=Pubs;" name="ConString"/>
      </connectionstrings>
    </configuration>

但是我帮助我
这个有效

<?xml version="1.0"?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5"/>
    </startup>
  <connectionStrings>
    <add name="pubs"
         providerName="System.Data.SqlClient"
         connectionString="server=(local);integrated security=SSPI;database=pubs" />
  </connectionStrings>
</configuration>