About Creating Subject Areas

There are several ways to create subject areas in the presentation layer.

Oracle recommends that you drag and drop a business model from the logical layer to the presentation layer, and then modify the presentation layer based on what you want users to see. You can move columns between presentation tables, remove columns that don't need to be seen by the users, or even present all of the data in a single presentation table. You can create presentation tables to organize and categorize measures in a way that makes sense to your users.

You can also duplicate an existing subject area and its corresponding business model. Or you can create an empty subject area.

Although each subject area must be populated with contents from a single business model, you can create multiple subject areas for one business model. Creating multiple subject areas for one business model makes it easier for the users to work with the content and create queries that span multiple subject areas.

There are many ways to create multiple subject areas from a single business model. One method is to drag a business model to the presentation layer multiple times, then edit the properties or objects of the resulting subject areas.

For example, suppose you have a business model called ABC that contains the Geography and Products dimensions. When you drag it to the presentation layer twice two subject areas are created with the default names ABC and ABC#1. You then edit the subject areas as follows:

• Rename the ABC subject area to DEF, then delete the Geography presentation hierarchy

• Rename the ABC#1 subject area to XYZ, then delete the Products presentation hierarchy

Users can then run queries that span the DEF subject area containing the Products hierarchy, and the XYZ subject area containing the Geography hierarchy.

When you query a single subject area, all the columns exposed in that subject area are compatible with all the dimensions exposed in the same subject area. However, when you combine columns and dimensions from multiple subject areas, you must ensure that you don't include combinations of columns and dimensions that are incompatible with one another.

For example, a column in one subject area might not be dimensioned by Project. If columns from the Project dimension from another subject area are added to the request along with columns that aren't dimensioned by Project, then the query might fail to return results, or cause the error, "No fact table exists at the requested level of detail: XXXX."