We will be using the Excel workbook we used in our earlier posts. Open the Excel file, you can find the link for download in my earlier posts or from blog Menu.
Most Data Models include data that is inherently hierarchical. The Olympics data is also hierarchical. It’s helpful to understand the Olympics hierarchy, in terms of sports, disciplines, and events.
For each sport, there is one or more associated disciplines (sometimes there are many).
And for each discipline, there is one or more events (again, sometimes there are many events in each discipline).
The following Table illustrates the hierarchy.
In this post we will create two hierarchies within the Olympic data. Then use these hierarchies to see how hierarchies make organizing data easy in PivotTables and in Power View in upcoming posts.
Create a Sport hierarchy
In Power Pivot, switch to Diagram View. Expand the Events table so that you can more easily see all of its fields.
- Press and hold Ctrl, and click the Sport, Discipline, and Event fields. With those three fields selected, right-click and select Create Hierarchy. A parent hierarchy node, Hierarchy 1, is created at the bottom of the table, and the selected columns are copied under the hierarchy as child nodes. Verify that Sport appears first in the hierarchy, then Discipline, then Event.
- Double-click the title, Hierarchy1, and type SDE to rename your new hierarchy. You now have a hierarchy that includes Sport, Discipline and Event. Your Events table now looks like the above screen.
- Still in Diagram View in Power Pivot, select the Hosts table and click the Create Hierarchy button in the table header, as shown in the following screen.
- An empty hierarchy parent node appears at the bottom of the table.
- Type Locations as the name for your new hierarchy.
- There are many ways to add columns to a hierarchy. Drag the Season, City and NOC_CountryRegion fields onto the hierarchy name (in this case, Locations) until the hierarchy name is highlighted, then release to add them.
- Right-click EditionID and select Add to Hierarchy. Choose Locations.
- Ensure that your hierarchy child nodes are in order. From top to bottom, the order should be: Season, NOC, City, EditionID. If your child nodes are out of order, simply drag them into the appropriate ordering in the hierarchy. Your table should look like the above screen.
Your Data Model now has hierarchies that can be put to good use in reports. In the upcoming posts we will learn how these hierarchies can make our report creation faster, and more consistent.
Stay tuned for more details, will come up with usage of hierarchy in my upcoming post.
Till then keep learning & practicing.