Specially
prepared information maps provide a metadata layer between the nontechnical
business user and the complexities of database structure and query
languages. Information maps are created by a data source administrator
in a centrally managed location so that you can easily define a report.
Authorized users who might be more advanced can access tables and
cubes directly. All data sources contain data items, which can refer
to calculations or physical data (tables or cubes). Data items in
information maps are described in common business terms that enable
both casual and professional report authors to easily build queries
that return consistent results. Reports can include query results
from more than one data source.
Each information
map includes one or more data items. For example, an information map
named
Order Information might
include standard data items such as
Order ID,
Product ID,
Unit Cost,
Order Date, and
Order Amount. You decide
which data items to use. You can select all of the data items in the
data source or a subset of data items.
You can also create
two types of custom data items:
-
You can calculate a new measure
that is based on one or more existing measures.
-
If the data source includes a time
hierarchy from a multidimensional data source, then you can create
one or more custom data items that are based on relative time.
In addition to explaining
how to use both standard and custom data items, this chapter explains
how to modify the query in these ways:
-
by changing the format used for
one or more data items
-
by using detail data instead of
grouped and aggregated data
-
by changing the aggregation method
used for one or more measures