Friday, September 21, 2012

Readings thoughts for 9/24

* Database : organized collection of data, typically organized in a helpful way.
* Database systems are managed by quality (accuracy, availability, usability).
* Virtually every technology uses databases.
* A database must be functional to qualify as a database management system (DBMS).
* SQL = the language of databases. It's not the most elegant, but it's cheap and easy to use.
* Database technology has kept current with technology in general.
* DBs work within other computer systems. An attempt in the 70s and 80s tried to build stand-alone DBMS but they were expensive and awkward.
* There is so many different kinds of DBs. I had no idea!
* Entity relationship model (ER model) : an abstract way to describe a database.
* Proposed by Peter Chen in 1976.
* Entities : things capable of independent existence with unique IDs. AKA nouns.
* Relationships : connect entities to each other. AKA verbs.
* Must be structured data (semi-structured data won't work)
* 3 normal forms : no repeating elements; no partial dependencies on a concatenated key; no dependencies on non-key attributes.

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