Database Reference
In-Depth Information
•
Each
Withdrawal Slip
may record one or many
Withdrawal Debits
.
•
Each
Withdrawal Debit
must be recorded by one
Withdrawal Slip
.
Business Sketch
We can get very creative on how we format the data model, such as the business sketch of
our account example on the following page where we use icons, sets, and pictures. There is
an icon for large documents, such as for
Bank Account Statement
, an icon for small docu-
ments, such as for
Deposit Slip
,
Check
, and
Withdrawal Slip
, and an icon for transactions
such as for the various credits, debits, and fee. The subtyping structures of
Customer
and
Account
are shown as sets, and there is a picture for the bank branch.
This model is less precise than the prior two because we are not showing cardinality but
instead showing arrows from the parent entity to the child entity (or double-sided arrows
for the many-to-many relationship between
Customer
and
Account
and between
Account
and
Bank Account Statement
). It is also less precise because we are connecting the ar-
rows to
Account
instead of the
Account
subtypes (e.g.,
Check Debit
connects to
Account
instead of
Checking Account
). However, this model could still be a great communication
tool with the business, especially if there are solid definitions for each of these terms.
For Dimensional
