This tool supports normalization based on functional dependencies. Schemas can be created, FDs specified, and the schemas then tested for various properties (e.g., find a minimal cover, find keys, check if they are in a particular normal form and find FDs that cause a violation if not, etc.) and decomposed further. Properties of decompositions (lossless-join and dependency-preservation) can be checked easily.
Importantly, the tool supports a concept of a refinement session, in which a schema is decomposed repeatedly and the resulting decomposition tree is then saved. For a given schema, a user might consider several alternative decompositions (more precisely, decomposition trees), and each of these can be saved as a refinement session. This provides a very flexible and convenient mechanism for trying out several alternative decomposition strategies.
A complementary tool to create and edit ER diagrams and to produce a relational schema with FDs and inclusion dependencies from such diagrams is under development. The normalization tool can also generate SQL-92 statements to create tables (with appropriate primary key and referential integrity constraints) corresponding to a set of schemas, FDs and (restricted) inclusion dependencies.
Together these two tools should support the paradigm of developing an ER diagram and then refining it using normalization. The goal is to enable a user to focus on the important issue of how to choose between alternatives in database design, rather than on the details of normalization algorithms. See the chapters on ER design, normalization and physical design/tuning in the text) for a discussion of design alternatives.
The tool can be run using the command designview. Examples are included in the directory programs/designview/examples.
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