R. Kelly Assignment – Week 4 Database Systems Management MGT 5151 Professor William Cross November 17, 2019 Normalization Factors Consider the following: What is normalization? What does it do? Why is normalization needed? Is there such a thing as "too much" normalization? Why or why not? Provide an example of proper normalization and one for poor normalization. Include SQL operations that would be more/less efficient for your examples. Normalization is what is used to organize data in a database. It’s used to create tables and set up relationships between tables rendering to the rules designed to make the database flexible by taking away inconsistent and redundant dependencies. When you have redundant data, it can cause space to be taken up in the database and can cause maintenance issues. If you have data in multiple places instead of one place, it must be changed in the exact same way in all places. For example, if you have a customer’s phone number only in the Customers table it would be easier to change, instead of having to change in multiple locations within the database. Rules for database normalization is called “normal form”. The first rule that is observed is called the “first normal form”. If you have three rules that are observed, it’s called the “third normal form”. Once you get to the third normal form, it’s usually considered the maximum level necessary for applications. Normalization needs multiple tables and if you have any redundancies, prepare the application to handle any problems that may deliver inconsistent dependencies. It’s important to have data normalization because it can cut back or wipe out data redundancy and it helps to maintain information in a rational database which may contain the same information in multiple places. Too much normalization can exist, and it can cause long queries and performance issues. When you have too much normalization it will allow all flag columns to turn into a foreign key which will point to another record that will display a message of true or false. This can result in hundreds of arms spreading throughout the database. One example is the reason for not creating a “City Table” which you would not need to add much information about a city. When you normalize a data, it should be as minimal as possible to prevent such unneeded information added to the normalization of the database. Below are the examples of Proper and Poor Normalization tables. 1NF form: Unnormalized Table: Student# 1255 7389 Advisor Jessup Hurst Adv-Room 613 527 Class1 001-08 101-08 First Normal Form: No Repeating Groups Student# 1255 1255 1255 7389 7389 7389 Advisor Jessup Jessup Jessup Hurst Hurst Hurst Adv-Room 613 613 613 527 527 527 2NF: Second Normal Form: Eliminate Redundant Data Students: Student# 1255 7389 Advisor Jessup Hurst Registration: Student# 1255 1255 1255 7389 7389 7389 Class# 001-08 025-01 050-02 101-08 111-02 114-01 Adv-Room 613 527 Class# 001-08 025-01 050-02 101-08 111-02 114-01 Class2 025-01 111-02 Class3 050-02 114-01 3NF: Third Normal Form: Eliminate Data Not Dependent on Key Students: Student# 1255 7389 Advisor Jessup Hurst Faculty: Name Jessup Hurst Room 613 527 Dept 32 32 Poor Normalization: Table: Student# 1255 1255 1255 7389 7389 7389 FirstName Nia Nia Nia Rosetta Rosetta Rosetta After normalization: Student# 1255 1255 1255 7389 7389 7389 Class# 001-08 025-01 050-02 101-08 111-02 114-01 LastName Jessup Jessup Jessup Hurst Hurst Hurst Class# 001-08 025-01 050-02 101-08 111-02 114-01 Student# 1255 1255 1255 7389 7389 7389 FirstName Nia Nia Nia Rosetta Rosetta Rosetta LastName Jessup Jessup Jessup Hurst Hurst Hurst This will not be efficient: Select FirstName, LastName where Class# = 001-08. Unable to have two classes for the same student.
