Download https://splunkbase.splunk.com/app/1603/ for drilldown examples.
also try below for example to drilldown from pie chart :
<drilldown> <!--<set token="state_name">$click.value$</set>--> <link> <![CDATA[ /app/myapp/myview1_2?form.state_name=$click.value$ ]]> </link> </drilldown>
@josephinemho, requesting you not to downvote a 6 year old post as the Examples App has changed over time, which is right now Splunk Dashboard Examples
You can search for more recent answers on Pie Chart Drilldown or post a new question instead.
Post Splunk Enterprise 6.6 Drilldown options are available directly in the UI Edit options. Nevertheless Simple XML code for drilldown still remains the same as previous versions: http://docs.splunk.com/Documentation/Splunk/latest/Viz/DrilldownIntro