by Ivan C
A relational database is a collection of files that are related in any form. Databases differ depending on how they are constucted or modeled. In the past models such as the hierarchical and network models were widely used. In the Hierarchical model the files were related as a parant-child relation, while the files in the network model were related as owners and members. Relational databases work by having two datasets and a common field. A database consists of tables, records or tuples, and fields or attributes. Records run horizontally on the rows of the tables while the attributes run vertically. A one-to-one, one-to-many, and many to many relationships are possible in a reltational database(Gilfillan, 2002). These reltaionships represent the instances of table x related to table y. Other types of relationships include an optional and mandatory relationship. To make table x easily access table y a key must be created. A key is a field or a combonation of fields that are unique to anyother that identify a specific record. A foreign key is similar to the primary key in which the foreign key lies in a table that points out the primary key of the another table. Databases are most useful when the data is transformed into information. For this to happen views, or virtual tables, must be created. Views allows us to access whole data or a subset of it. They are useful becuase it allows users to see data but restrict them from seeing personal or confidentall information. This way data is hidden and safe from being manipulated(Gilfillan, 2002).
This article clearly informed the reader about relational databases. It gave good representations and examples to help the reader understand the subject better. It also defined key terms and provided links within the article to describe terms in more depth. I liked how this article explained the simple aspects of a relational database ranging from relationships and candidate keys while still informing readers about the more difficult ones. It is important to know how databases benefit a business but it is more important to know what a database is and how it works so it could evolve into a more powerful tool than it already is. This article is related to the class in which it builds the foundation of what we will learn throughout the quarter. It will help us understand every angle of a database.
Gilfillan, I. (2002). Introduction to Relational Databases. SQL Etc. , 3. Retrived September 30, 2011 from http://www.databasejournal.com/sqletc/article.php/1469521/Introduction-to-Relational-Databases.htm