||To give consistency over the database
development, all modeling should be carried out at the conceptual
level. Performing database modeling at the conceptual level is
closer to the business domain that the database being designed is
required to satisfy.
||Conceptual Models allow for greater
flexibility in the design process, by working with entities and
their relationships to one another allows for changes to be made
once, change the name of a column or its attributes, which may
result in multiple changes to the physical model that will be
handled through the toolset.
||By working on the physical level
multiple copies of the database schema would need to be kept or a
migration path developed, one for each of the target databases,
which would soon get out of sync, as each required target database
generally has their own extensions and limitations that need to be
taken into account. The number of changes that would need to be made
to a physical model if for example the Policy Number column
attributes changed would be fairly high and prone to possible
errors, but would only require one change at the conceptual level.
||Currently the modeling tool of choice is
PowerDesigner from Sybase, this provides a flexible platform for
describing the conceptual level of the database, and has built in
capability to generate approximately 38 different physical database
models, with the option to create your own physical database
definition if the need arises.