BOTTOM-UP DATABASE IMPLEMENTATION

At the “bottom-up” approach is carried out structural design of the bottom-up. This process is called synthesis process, an attempt to obtain a whole, adequately reflects the description of the subject area, based on the description of its parts. Stages of database design by ” bottom-up ” design shown in Figure 1.

Figure 1 – Steps of designing a database by ” bottom-up ” design

DLM – datalohic model model; NF – normal form; – Information and logical domain model; MDB – database model.

Work for the relational database starts with the determination of the properties of objects (entities attributes) domain, which are based on the analysis of the links between them are grouped into relational relationship (table) showing these objects (if we design the structure of a relational database).
Typically, 2 – 3 relational attitudes associated with each other.
The redundancy data in non-normalized pattern – repeating the data in the database.
To the resulting database structure (DLM) did not have a variety of abnormalities when adding, updating or deleting data as a result of redundancy, it is necessary to verify each of the resultant relations scheme at least for compliance with 3NF. If the relationship does not correspond to this circuit condition, and they usually do not match, the process necessary to carry out normalization.
A significant amount of measures to normalize relations relational schemas even gave the second name of the method of “bottom-up” design. This method is often referred to by the “normalization”. Fundamentals of the theory of normalization has created E. Codd.
Normalization – is a design process in terms of the relational data model, the method of successive approximations to a satisfactory set of schemes.
Thus, for successful normalization (to 3NF) is necessary based on the analysis domain (domain analysis of documents) for each relational schema relationships:
- Identify potential keys;
- See the repeating groups and atomic attributes;
- Lead circuits relation to 1NF;
- Determine the functional relationships between non-key attributes and primary key;
- To determine the partial functional dependencies;
- To carry out decomposition (division) of the respective schemes for relations deletions partial functional dependencies;
- See transitive dependencies between non-key attributes and primary key;
- Exclude transitive dependencies by decomposition of the corresponding schemes of relations.
Implementation of these activities is quite time-consuming process. For example, the identification of the complete set of functional dependencies require knowledge of set theory and predicate logic.
To bring schemes relations to higher normal forms necessary to conduct additional studies to determine the subject area determinants of relationships, to identify multi-valued dependencies between the attributes of the relationship, the connection relationships.

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