title: How to use different Web.config value by different configuration dynamically and use Base.config (.NET Framework)
body: <p>I want to use different Web.config when program run in different configuration (Debug Release)
  I add Web.Debug.config,Web.Release.config and Web.Base.config by myself</p>
  <p>When value doesn't set,use Web.Base.config</p>
  <p>Web.Base.config set Timeout value =&gt; <code>&lt;add key=&quot;Timeout&quot; value=&quot;30&quot;/&gt;</code>
  Web.Debug.config doesn't set Timeout value
  Web.Release.config set Timeout value =&gt; <code>&lt;add key=&quot;Timeout&quot; value=&quot;60&quot;/&gt;</code></p>
  <p>I want
  run in Debug configuration,Timeout is 30 (from Web.Base.config)
  run in Release configuration,Timeout is 60 (from Web.Release.config)</p>
  <p>How to do this in .NET Framework(4.6.2)</p>