Then, in the same table, is a Manager ID
field, which ties back to the Employee ID of that person??™s manager. The employee
with either a blank Manager ID or a Manager ID that is the same as the Employee ID
is the top of the hierarchy. Everyone else falls below that.
As an example, take a look at Figure 3-3. This shows a simple organization chart
for a very small company. Note that some Vice Presidents don??™t have any Directors
and that different chains contain a different number of levels.
Table 3-2 shows the relational structure that supports the organization chart from
Figure 3-3. Note that a hierarchy of any level can be represented in a self-referencing
table, which is a table in which one field is tied to another (usually the primary key).
Fact Tables
While dimension tables represent how users want to see data, fact tables represent
the data users want to see. Facts are almost always numeric values such as dollar
sales, unit sales, employee turnover, inventory levels, portfolio churn rate, and so
forth. Often these values are fully additive, meaning that a value such as dollar sales
40 B u s i n e s s I n t e l l i g e n c e w i t h M i c r o s o f t O f f i c e P e r f o r m a n c e P o i n t S e r v e r 2 0 0 7
Torrey
Donald
Raghu
VP Human
Resources
Molly
VP Sales
Hannah
Director Director
Director
Yoshi Mario
Team Leader
Benefits Admin
Payroll Clerk
Patty
Benny
Hailey
Admin Assistant
CEO
Figure 3-3 A simplified organizational chart shows that the hierarchical structure of a
parent-child dimension is not predictable as far as the number or consistency
of levels.
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