Addison Huggins
Unit 4 Research assignment 1
July 24, 2014
The definition of Functional dependency is when one attribute in a relation uniquely determines another attribute. This can be written A -> B which would be the same as stating "B is functionally dependent upon A." While I was looking online for a good example of Functional dependency I came across one, the example comes from the website. http://databases.about.com/cs/specificproducts/g/functdep.htm in this example and I quote ” In a table listing employee characteristics including Social Security Number (SSN) and name, it can be said that name is functionally dependent upon SSN (or SSN -> name) because an employee's name can be uniquely determined from their SSN. However, the reverse statement (name -> SSN) is not true because more than one employee can have the same name but different SSNs.” Transitive dependency occurs when there is an indirect relationship that causes a functional dependency. While looking this up on the internet, it is hard to find a good example but in time I did. The example comes from http://databases.about.com/od/specificproducts/g/transitive-dependency.htm and from the website the example is and I quote “”A -> C” is a transitive dependency when it is true only because both “A -> B” and “B -> C” are true.” Demoralization is a strategy that database managers use to increase performance in their database. This is used to reduce certain types of problems that might come along with database queries that combine data from different tables into a single table.