Guides/ReportDesign/9.0-Misc-Tab.md
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##9.2 Drill-Downs
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-The fundamental difference between a main report and a sub-report is the **drill-down key** field. Setting this field will enable a report to be used as a sub-report. So let's start by creating a report in the Report Designer.
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+The fundamental difference between a main report and a sub-report is the **drill-down key** field. Setting this field will enable a report to be used by another report as a sub-report. There is no other difference between a report and a sub-report. Also, a sub-report can have sub-reports of its own. So let's start by creating a report in the Report Designer.
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###9.2.1 Designing the sub-report
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###9.2.2 Setting the drill-down key
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-We have a report with three fields created. Now we will set the **drill-down key**. We can either set one drilldown key or both of them. We can also select whether we want to ignore the first key and just use the second one. Ignoring the first drilldown key can allow, for example, a CategoryName and ProductName to be sent to the sub-report, but instead of displaying just records for that CategoryName and ProductName, it will show all records with the specified ProductName, regardless of category. The main report will still require both keys to be passed, which we will cover below as well. As another example, if you have a field you do not wish to expose to users, such as an ID field, then you can specify that the drilldown link appears on a name field (such as ShipCountry) and pass the ID field to the sub-report without ever exposing it to the user.
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+We have a report with three fields created. Now we will set the **drill-down key**. A **drill-down key** is simply a field which the sub-report looks through to match values when it is passed a value by some other report. Izenda does not check to see if the value passed is valid or logical, it simply looks through the **drill-down key** field to see if there are any matches. If there are matches, it returns records associated with that match as if we ran a filter which equals that value. If there are no matches, it returns a page which states "No Results".
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-For now, we will set the drill-down keys to ShipCountry and ShipCity and we will not ignore ShipCountry.
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+We can either set one drilldown key or both of them. A sub-report with one key set will only search through the first **drill-down key** field for a match. A sub-report with both **drill-down key** fields set will search through the first (top) field, obtain a set of matches, then search those matches for values in the second **drill-down key** field. This means that if the first field returns no matches at all, the second field will have no valid records to search through.
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+We can also select whether we want to ignore the first key and just use the second key. This means that we will pass the first value to the subreport, but then the sub-report ignores this value and immediately searches through the second **drill-down key** field as if the first **drill-down key** field returned ALL results. The main report will still require both keys to be passed, which we will cover below as well. As an example, if you have a field you do not wish to expose to users, such as an ID field, then you can specify that the drilldown link appears on a name field (such as ShipCountry) and pass the ID field to the sub-report without ever exposing it to the user.
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+For now, we will set the drill-down keys to ShipCountry and ShipCity and we will not ignore ShipCountry. Please see [this link](http://wiki.izenda.us/FAQ/Questions/sub-reports-and-drilldowns) for more detailed information about drilldowns.
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_**Note:** Earlier versions of Izenda reports only allow one drilldown key to be used._
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