Database Reference
In-Depth Information
Product or service of interest to the enterprise. It often refers to what
the organization makes that keeps it in business. That is, “
What
is im-
portant to the business?”
Product, Service, Raw Material,
Finished Good, Course, Song, Pho-
tograph, Title
What
Calendar or time interval of interest to the enterprise. That is, “
When
is the business in operation?”
Time, Date, Month, Quarter, Year,
Semester, Fiscal Period, Minute
When
Location of interest to the enterprise. Location can refer to actual
places as well as electronic places. That is, “
Where
is business con-
ducted?”
Mailing Address, Distribution
Point, Website URL, IP Address
Where
Order, Return, Complaint, With-
drawal, Deposit, Compliment, In-
quiry, Trade, Claim
Event or transaction of interest to the enterprise. These events keep
the business afloat. That is, “
Why
is the business in business?”
Why
Documentation of the event of interest to the enterprise. Documents
record the events such as a Purchase Order recording an Order event.
That is, “
How
does the business keep track of events?”
Invoice, Contract, Agreement,
Purchase Order, Speeding Ticket,
Packing Slip, Trade Confirmation
How
Entity instances are the occurrences or values of a particular entity. Think of a spreadsheet
as being an entity where the column headings represent the pieces of information about the
entity. Each spreadsheet row containing the actual values represents an entity instance. The
entity
Customer
may have multiple customer instances with the names
Bob
,
Joe
,
Jane
, and
so forth. The entity
Account
can have instances of
Bob's checking account
,
Bob's savings
account
,
Joe's brokerage account
, and so on.
Entities can exist at conceptual, logical, and physical levels of detail. We will go into detail
into conceptual, logical, and physical modeling in
Section II
of this topic. A short defini-
tion, however, of each level will be needed for you to benefit from the following discus-
sion. The conceptual means the high level business solution to a problem frequently defin-
ing scope and important terminology, the logical means the detailed business solution to a
problem, and the physical means the detailed technical solution to a problem. “Problem”
usually refers to an application development effort.
For an entity to exist at a conceptual level, it must be both basic and critical to the business.
What is basic and critical depends very much on the scope of the effort we are modeling. At
