Week 4 Reading Notes

Database

·      An organized collection of data

o   Inputs, stores, retrieves, and manages large quantities of information

·      Database management systems

o   Applications that interact with other applications and the user to capture and analyze data

·      Database servers

o   Dedicated computers that hold only the database and the DBMS software

§  RAID used for data recovery

·      General vs. Special Purpose DBMS

o   General meets the needs of as many applications as possible which lowers the price because more people are paying for the upkeep

o   In certain situation when only a specific application is warranted it might be unnecessarily expensive to pay for an all-encompassing DBMS when a specified one would work better

·      Navigational DBMS

o   Searched records by navigating relationships

·      Relational DBMS

o   Data would be stored in tables where information could be deleted or changed at will

§  A “key” was created and that is how records were sorted and searchable

·      SQL

o   Split data so that it would not have to all be stored in the same place

o   Data as objects

·      Databases can be classified by:

o   Content

o   Application area

o   Technical aspect

·      Aspects to consider when building a database

o   Structure of the information that the database will hold

o   Relevant data structure schema

o   Performance, scalability, recovery, and security

·      Internal vs. external views

o   What the users have access to view, there can be different views for different users as well

·      Security and access: controlling who can access what

·      I was a little confused on how the Navigational and Relational DBMS’ worked…

Entity-relationship model

·      Model for describing data in a database

·      Data components are linked together through relationships

·      Conceptual data model

o   Seeks to create structural metadata commonality

·      Logical data model

o   Operational and transactional data

·      Physical data model

o   Needs to be detailed enough to build a database off of

·      Entities=nouns, relationships=verbs

o   Verbs link 2 nouns

o   Both have uniquely identifying attributes

·      I understand the basis of this relationship: that data are linked together through relationships, but I am a bit confused on the inner workings (like the models mentioned above).

Database Normalization Process

·      This article was very confusing to me. It was heavily reliant on various charts and diagrams, however with the broken link we did not have access to any of the images and so the text explanations did not make any sense.  I tried to read through but without the images to see what exactly the author is referring to, I was completely lost.