My first Publication Agile-Data-Warehouse-Design-eBook | Page 58

Modeling Business Events
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You can download a copy of the BEAM✲Modelstormer spreadsheet from
modelstorming.com . It contains template BEAM✲ (example data) tables linked to
formulas for generating customizable SQL DDL and simple table/entity graphics.
You can use the DDL to define physical database tables or export your BEAM✲
model to other database modeling tools to produce star schemas.
3. Describe the Event: Using the 7Ws
BEAM ✲ obeys the maxim “show, don’t tell” to describe and model an event using
event stories rather than lengthy descriptive text. But before you can ask for useful
example stories you need one more detail. You need to discover when the event
occurs. You find out by asking your second simple “W” question: a when question.
Every event story
needs a when detail
When?
Every event story has at least one defining point in time. No meaningful BI analysis
takes place without a time element. Therefore, immediately following the discovery
of an event, you should ask for its when detail. You do so by repeating the main
clause of the event to the stakeholders as a question, with a “when” appended or
prepended:
You discover when
details by asking a
when question
CUSTOMER orders PRODUCT when?
or
When do CUSTOMERs order PRODUCTs?
To which the stakeholders might respond (if you’re lucky):
On order date.
This is certainly what you are hoping for: a prepositional phrase containing a
preposition: “on” followed by a noun: “order date.” If they respond with actual
dates/times, ask what these should be called. You are looking for a noun to name
this detail; after you have it you can then use the date/time values for example
stories to help you understand the time nature of the event. The general form of a
when question is: “Subject Verb Object when?” or “When does a Subject Verb
Object? What do you call that date/time?” The required response is in the form:
“on/at/every Time Stamp Name” You are looking for a
The preposition on used with a when detail implies that the detail is recorded as a
date, suggesting that the time of day is not available or is not important. An at
preposition implies that time of day is recorded and is important. Whenever stake-
holders give you example when values you should check that prepositions and
examples match; so that event stories can be read correctly. When prepositions
preposition and a
name for the when
detail
contain clues to the
level of time detail
available/needed