#Sub-reports and Drilldowns
##Question
How do sub-reports and drilldowns work? What are the options for sub-reports?
##Answer
Sub-reports are simply regular reports with one extra step. Their defining trait is the presence of a drilldown key. This is a key field that will be used by main reports to send information to the sub-report. This is done on the Misc tab of the report designer. There is also a short example of how to create a basic sub-report and link it to the main report at that link. The Advanced Field Settings box is where you link a main report to a sub-report.
###Sub-reports on charts
In addition to creating drilldowns for your main report items, you can create sub-reports for pie charts and bar charts as well. Currently, these only support a single key value, specified via the Label field. These will work with reports that have one drilldown key defined, but not ones with two keys defined.
Note: Bar charts and pie charts do not support drilldown effects. They will always have the "Link" effect.
###Sub-reports on maps
You can also create a drilldown on the Maps tab that will trigger using the specified effect. You can learn more about the maps feature at the link above.
###Sub-reports on gauges
Gauges can also accept sub-reports and will use the Name field in order to select the appropriate drilldown key. See the Gauge tab for more. You can have a drilldown effect defined here as well. Again, creating a sub-report on a gauge is just like anywhere else. They only accept one drilldown key currently as well.
###Sub-reports on forms
Finally, you can choose to use sub-reports in your FORMS report too. You can see the Izenda Forms section for more information about this feature. Drilldowns are defined in two ways, described in the article above. Sub-reports that you specify in the form with a declaration such as "[subreports/top products by state]" do not get a drilldown key and will be treated as a stand-alone report. You can reference the column alias in order to use drilldown key driven sub-reports.
###Using a URL instead of a sub-report
In addition to drilling down to a sub-report, you can also explicitly define a URL to open. This can be an external URL or an internal URL to the reporting application. You can use field brackets in the URL as well to pass data through query string parameters. (e.g. ReportViewer.aspx?rn=Subreport&master=MainReport&ddkvalue=[OrderID]&ddkvalue2=[ShipCountry]).
###Settings applicable to drilldowns