WEEKLY QUESTIONS FOR CHAPTER SIX- Databases and Data Warehouses

1.    List, describe, and provide an example of each of the five characteristics of high quality information.

a.       Accuracy- the values are correct, the spelling is correct and everything is recorded properly.

b.      Completeness- no values are missing

c.       Consistency- all information is in agreement

d.      Uniqueness – each transaction/entity/ event is represented only once in the information.

e.      Timeliness- the information is current (ie updated hourly, weekly or daily)

2.    Define the relationship between a database and a database management system.

A Database is an organised collection of data. It is the actual infomation including the tables, fields and reports organised in a logical way. Here is a picture of one:

Whereas a DBMS is a group of programs that manipulate the actual database and provide an interface between the database/users of database and other application programs.It is the system that actually runs the database. (ie Microsoft Access)
To learn the basic concepts of DBMS see this tutourial:
www.quackit.com/database/.../database_management_systems.cfm 

3.    Describe the advantages an organisation can gain by using a database.

a.       increased flexibility- databases allow each user to access the information which best suits their individual needs

b.      increased scalability and performance- only a database can ‘scale’ to handle the massive volumes of information.

c.       Reduced information redundancy- databases ensure no duplication of information

d.      Increased information integrity or quality- integrity constraints are rules in a database that help ensure the quality of information

e.       Increased information security- databases help organisations protect its information from unauthorised users or misuse.

4.    Define the fundamental concepts of the relational database model.
A Relational database is a form of logically related two dimensional tables (rows/columns).

·         Entity- is a person/place/ thing/ transaction/ event about which information is stored. (record=column)

·         Attributes- or fields or columns, are characteristics or properties of an entity class

·         To manage and organise various entity classes within the relational database model, developers must identify primary and foreign keys and use them to create logical relationships.(rows)

o   Primary key- a field that uniquely identifies a given entity in a table. They are important because they provide a way of distinguishing each entity in a table.

o   Foreign key- is a primary key of one table that appears as an attribute in another table acts to provide a logical relationship between the two tables.
To learn about the specifics of creating a relational data base go to this site:
http://www.anchor.com.au/hosting/support/CreatingAQuickMySQLRelationalDatabase

5.    Describe the benefits of a data-driven website.

a.       Development- it allows the website owner to make changes without having to rely on the developer or know about specific HTML programming. You need virtually no training to use this. and it updates products/prices automatically since it is connected to a database.

b.      Future expandability- Data driven websites allows the site to grow faster than would otherwise be possible because changing the layout, displays and functionality is easier.

c.       Minimising Human Error- data driven websites have error trapping mechanisms to ensure that required information is filled out, entered and displayed in the correct format.

d.      Cutting production and update costs- changing the content is more convenient, anyone can do it, its more affordable and it is quicker to change.

e.       More efficient- the system keeps track of templates to improve reliability and stability of the website. You are able to search/ enter a query into the database.

f.       Improved stability- content is never lost unlike static websites.

6.    Describe the roles and purposes of data warehouses and data marts in an organization.

 A data warehouse is a logical collection of information gathered by many different operational databases which helps support business analysis activities and decision making tasks. The main purpose is to aggregate information throughout an organisation into a single repository which allows employees to make decisions and undertake analysis activities. They store the same information as databases but in an aggregated form (ie totals, counts, and averages) suitable to help in decision making. Data warehouses use extraction, transformation and loading (ETL) which extracts information from internal and external databases, transforms the information using a common set of enterprise definitions and loads the information into a data warehouse.

Data warehouses send sub sets of information to Data marts . Note that data warehouses have an organisational focus and data marts have focused information subsets particular to the needs of a given business unit (ie Finance, Production, Operations).

To learn more about Data Warehousing it is useful to watch this video:

http://www.youtube.com/watch?v=eiRhRxPuEU8