Database Theory

Jason Combs

Unit 3 Assignment

IT-163-03: Database Management

Professor Joan Alexander

May 5, 2012

Database Theory

In the world of databasing, there are designs and concepts that incorporate database theory. Within that theory are the reasons for why databases are used. Databases in their most basic form are used to collect and store information. In the business world, this often means tracking products, services, and employees, along with projects, customers, and goods.

Part of the design of databases are proper stucture and hierarchy in order to prevent data redundancy, or the repetition of data within the database, which causes unneccesary database file sizes and unwanted extraneous data when that data is queried. This is why a concept called Relationships was developed for databases. According to Microsoft, a software developer who created Microsoft Access, "One of the goals of good database design is to remove data redundancy (duplicate data). To achieve that goal, you divide your data into many subject-based tables so that each fact is represented only once." (Microsoft, Guide to Relationships) From this concept, there was developed three relationships: One to One (1:1), One to Many (1:M), and Many to Many (M:M). In simplistic terms, using these relationships in a database reduces the work needed to create, work with, and update the tables within a database. By linking together smaller tables that use related data, making changes to one table will affect subsequent queries of the data across the board.

A query is, at its most basic form, a question one asks a database in order to get data. When you query a database, the database program will search through its tables to find the information that was requested, and then display that data for the user. For example, if you have a database that contains contact information for employees at your place of business, and you ask the database to return information on anyone working on a...