Reading Notes 9-22

Database 
- An organized collection of data for one or more purposes, usually in digital form.
- Refers to both the way its users view it and to the logical and physical materialization of its data, content, in files, computer memory, and computer data storage.
- The database concept has evolved since the 1960s to ease increasing difficulties in designing, building, and maintaining complex information systems.
- Relational model (1970), insisted that applications should search for data by content, rather than by following links.
   - This appears to be a key development in the history of databases because it gives the users a more effective way in searching for the information they want.
- A database management system is a system that allows to build and maintain databases, as well as to utilize their data and retrieve information from it. Can be categorized according to the database models that they support.

Entity relationship model
- Database modeling method used to produce a type of conceptual schema or semantic data model of a system.
- A relationship captures how two or more entities are related to one another.
- First stage of an information system designs uses to describe information needs or the type of information that is to be stored in a database.
- An entity may be defined as a thing which is recognized as being capable of an independent existence and which can be uniquely identified.

Database normalization process
- 3 normal forms: 1. No repeating elements or groups of elements. 2. No partial dependencies on a concatenated key. 3. No dependencies on non-key attributes.
- Some documents can be transformed into databases to organize information more effectively.
   - This is a good example to show how information can be transformed into a database without being lost in order to provide.
- NF1 addresses two issues: 1. A row of data cannot contain repeating groups of similar data (atomicity) and 2. Each row of data must have a unique identifier (Primary Key).