Suzanne works as a Database Designer for DataOneWorld Inc. She is assigned the task of ecomposing the
components of a database, but she has to ensure that all the components are decomposed to only some
extent. Which of the following approaches will she use to accomplish the task?
A.
Mixed approach
B.
Inside-out approach
C.
Top-down approach
D.
Bottom-up approach
Explanation:
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 allthe 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 withgradual refinements following the top-down approach or
extending a portion with concepts that are not yet represented following the bottom-up approach.
Answer B 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 D is incorrect. In a bottom-up approach, thepreliminary specifications are broken down into smaller
components so that each component describes a basicfragment 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 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.