Merlyn works as a Database Administrator for DOW Inc. She is currently designing a database. She
wants to break down the preliminary specifications into smaller components so that each
component describes a basic fragment of the specifications. Which of the following approaches is
she using?
A.
Inside-out approach
B.
Top-down approach
C.
Mixed approach
D.
Bottom-up approach
Explanation:
In a bottom-up approach, the preliminary specifications are broken down into smaller components
so that each component describes a basic fragment of the specifications. These components are
then represented by schemas, some of which may consist of single concepts. The schemas are later
obtained to be integrated together until a final schema is obtained.
Answer C is incorrect. In a mixed approach, the designer decomposes the requirements into a
number of components, as in the bottom-up approach, but not to the extent where all the concepts
are separated. At the same time, a skeleton schema is defined containing the main concepts of the
application. This skeleton schema gives a unified view of the whole design and helps the integration
of schemas developed separately. Then the designer examines separately these main concepts and
can proceed with gradual refinements following the top-down approach or extending a portion with
concepts that are not yet represented following the bottom-up approach.
Answer A is incorrect. Inside-out approach can be regarded as a particular type of bottom-up
approach. It begins with the identification of only a few important concepts and, based on these, the
design proceeds, spreading outward ‘radially’. First the concepts nearest to the initial concepts are
represented, and a user then moves towards those further away by means of ‘navigation’ through
the specification.
Answer B is incorrect. In a top-down approach, a schema is created through a series of successive
refinements, starting from the first schema, which is gradually expanded by using appropriate
modifications that increase the detail of the various concepts. Moving from one level to another, the
schema is modified using some basic transformations called top-down transformation primitives.