如果第一个appender无法记录消息，请在log4net中设置另一个appender

Question

我已经添加了一个appender来使用log4net登录SQL Server，但是如果连接到数据库时出错，我想在应用程序事件日志中添加日志消息。

有没有办法实现这个目标？

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,Log4net"/>
  </configSections>
  <log4net>
    <root>
      <level value="DEBUG" />
      <appender-ref ref="ADONetAppender" />
      <appender-ref ref="EventLogAppender" />
    </root>
    <appender name="ADONetAppender" type="log4net.Appender.ADONetAppender">
      <bufferSize value="100" />
      <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
      <connectionString value="Data Source=PIYUSH-V;initial Catalog=Logs; Integrated Security=True;"/>
      <commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message],[Exception]) VALUES (@log_date, @thread, @log_level, @logger, @message, @exception)" />
      <parameter>
        <parameterName value="@log_date"/>
        <dbType value="DateTime"/>
        <layout type="log4net.Layout.RawTimeStampLayout"/>
      </parameter>
      <parameter>
        <parameterName value="@thread"/>
        <dbType value="String"/>
        <size value="255"/>
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%thread"/>
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@log_level"/>
        <dbType value="String"/>
        <size value="50"/>
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%level"/>
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@logger"/>
        <dbType value="String"/>
        <size value="255"/>
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%logger"/>
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@message"/>
        <dbType value="String"/>
        <size value="4000"/>
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%message"/>
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@exception"/>
        <dbType value="String"/>
        <size value="2000"/>
        <layout type="log4net.Layout.ExceptionLayout"/>
      </parameter>
    </appender>

    <appender name="EventLogAppender" type="log4net.Appender.EventLogAppender">
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline"/>
      </layout>
    </appender>    
  </log4net>
</configuration>