In [4], the authors stated that we have two approaches in database schema design. One is called top-down design approach, and the other is called bottom-up design approach. Top-down approach is currently used most extensively in commercial database application design; this involves designing a conceptual schema in a high-level data mode, such as the ER model, and then mapping the conceptual schema into a set of relations using mapping procedures. Although this kind of approach is very effective and attractive in handling complex data modeling problem, this is not suitable for the purpose of illustrating data-dependency in our tutorial system; this is because the mapped relational schema from ER model is usually broken down to certain normal form, this is undesirable for explaining data-redundancy concept and hence do not have enough contrast to illustrate the idea of functional dependency. Therefore, we found that for educational purpose, we have chosen the bottom-up design approach in our illustrative example.
Bottom-up approach is a technique that is a more purist approach, according to the authors in [4]. It views relational database schema design strictly in term of functional and other types of dependencies specified on the database attributes. After the database designer specifies the dependencies, a normalization algorithm is applied to synthesize the relation schemas. Since this approach is purely focusing the use of data-dependency, this is a very attractive approach in our example design.