normalization :: essays research papers

Normalization of the Lowe's Inventory Information System Database As a database grows in size and complexity it is essential that order and organization be maintained to control these complexities and minimize errors and redundancy in the associated data. This goal is managed by a process referred to as normalization. Normalization permits us to design our relational database tables so that they "(1) contain all the data necessary for the purposes that the database is to serve, (2) have as little redundancy as possible, (3) accommodate multiple values for types of data that require them, (4) permit efficient updates of the data in the database, and (5) avoid the danger of losing data unknowingly (Wyllys, R. E., 2002).". As a prelude to normalization, the database modeler researches the company and current database uses to determine the requirements for the new database. Table elements and relationships are determined, and candidate keys reviewed and established for the tables. The process of database normalization then begins. Databases can attain varying degrees of normalization classified as 1NF, 2NF, 3NF, 4NF, 5NF, and BCNF, however for practicality and in staying with the layout of our Lowe's inventory database, only the first through third normal forms or 1NF – 3NF will be addressed. First, a balance must be struck between data accessibility with regard to performance and maintenance and the concerns of data redundancy. To accomplish this and normalize the Lowe’s database, the supply and retail sides of the database were combined and the tables set in first normal form. In first normal form, the tables were formatted to ensure that the data within them was atomic i.e., ensuring that it was in its simplest form and had no repeating groups. A concatenated PK characterizes tables in 1NF and these tables can have partial and transitive dependencies. Decomposition from this point helps to eliminate redundancy as the modeler works toward a defined goal based on business rules and individual needs. The tables were next moved to second normal form, again undergoing a review where efforts were taken to reduce the amount of redundant data by extracting and placing it in new table(s). Here, each key component is written on a separate line, with the original key written on the last line. All dependant attributes then follow their perspective keys. This process is used to eliminate partial dependencies which are not allowed in 2NF. Finally, the tables were set into third normal form by ensuring that no non-identifying attributes were dependent on any other non-identifying attributes.