Reading Notes (Sept 24-30)

Reading 1: http://en.wikipedia.org/wiki/Database

-Databases are organized collections of data
-Software includes Oracle, SQL Server, and Microsoft Access
-XML is current most popular database file system
-Can be both physical or digital, usually refers to digital in current society
-Cloud Databases are the new and upcoming style format for digital databases
-Database efficiency depends wholly on computing power of output device
-Security enacted through encryption
-Database Management Systems are the method through which we decrypt and understand database materials
-Models include Hierarchical, Network, Inverted File and Relational
-Originally Databases grounded in physical storage, now more done in clouds and internet storage

Reading 2: http://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model

-Refers to abstract ways to describe databases
-Diagrams often used to extract information processing in database systems
-Three-headed approach:Conceptual, Logical, and Physical models
-Items are related to each other through series of key words (married, performed, etc)
-Revolves around ownership and possession
-Diagramming tools include MagicDraw and dbForge
-Cannot be used for semi-structured data
-Studies show, limitations have caused model to be less favored in relation to Enhanced Entity-Relationship Models, particularly in the business world

Reading 3:http://www.phlonx.com/resources/nf3/

-First Normal Form - No repeating elements
-Repeating elements are items with similar attributes and interferes with atomicity of database
-Atomicity - indivisibility of attributes into similar parts
-In NF1 each row of data must have a unique identifying key
-Referred to as Primary Key
-Second Normal Form -No Partial Dependencies on a Concatenated Key
-Focused on the Orders Table Structure
-Order_date and Order_id columns are the key problems in the Second Normal Form, often missing and disrupting database systems
-By switching orders to single-column primary key, NF2 can be appeased
-Third Normal Form - No Dependencies on Non-Key Attributes
-Sorting by secondary attributes causes issues when retrieving data from the database
-Removes context and can disrail the transfer of information
-Only primary relevant attributes can be used to recall and construct databases