Week 6 Post - Castonguay - Group A

Relational Database Theory

In 1970, a mathematician working at IBM named Edgar F. Codd published a paper that would change the future of technology. His paper showed how information stored in large databases could be accessed without knowing where the information was in he database or how it was structured. Basically, his paper brought up he new ides of relational databases. Before this time, databases were used in a predictable way that retrieved the same information over and over again. Only computer specialists were able to get specific information from computers. After Codd, any person could now get information from computers without knowing where it came from on the computer. his made people more able to focus on what hey were doing rather than accessing the information on their computers. After Codd published this theory, it needed to be tested. Many companies promoted it and much research was put into it. Following, many different types of relational databases were invented such as System R, SQL, and DB2. The DB2 family of relational databases handles billions of transactions every day and is one of IBM's most successful software products. Because of his ideas, Codd was named an IBM fellow and the Turing Award, which is considered the "Nobel Prize of computing."

A relational database organizes information on computers based on the relational model of data. Data is organized into one or many tables of rows and columns where each row has a unique key. In a database, each entity type has its own table with rows and columns. The rows represent the instances of that entity and the columns represent the attribute values describing each instance. Rows in other tables can be linked to each other with their unique keys. This is done by storing he original row's unique key as an attribute of the secondary row. In relational databases, rows are contain "tuples" and columns contain "attributes". The figure to the left shows how users interact with a relational database.

In relational database theory, there are five normal forms. These forms represent guidelines for record design and are designed to prevent update anomalies and data inconsistencies. The first normal form deals with the "shape" of a record type. The second and third normal forms deal with the relationship between non-key and key fields. The fourth and fifth normal forms deal with multi-valued facts which could correspond to a many-to-many relationship or a many-to-one relationship.

Comments

Kaili Yue- I really enjoyed your graphic showing what a relation, attribute, and tuple are. It helped me visualize the organization of relational databases much better!

J Schwakoff - I think your post helped me understand relational databases more than anything I found online. This was a difficult topic for me to completely grasp and you explained it in a much more understandable way than most!

Catherine Stephens - I learned about tab delimited files in your post, which were used before relational databases. Here, each entry was separated with a vertical bar. It is clear to notice how hard it would be to search for specific information in a file like this.

Resources

Kent, William. "A Simple Guide to Five Normal Forms in Relational Database Theory." Bkent.net. 1996. Web. 09 Feb. 2015.

 "The Theory of Relational Databases." IBM.com. Web. 10 Feb. 2015.