Week 7 Questions

Databases and Data Warehouses

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

Characteristic	Description	Example
Accuracy	Are all the values correct?	Is the name spelled correctly? Is the dollar amount recorded properly?
Completeness	Are any of the values missing?	Is the address complete including street, city, state and postcode?
Consistency	Is aggregate or summary information in agreement with detailed information?	Do all total fields equal the true total of the individual fields?
Uniqueness	Is each transaction, entity and event represented only once in the information?	Are there any duplicate customers?
Timeliness	Is the information current with respect to the business requirements?	Is information updated weekly, daily, or hourly?

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

A databse maintains information about various types of objects, events, people and places. Organisational information is stored in a database. Applications and programs, such as supply chain management systems and customer relationship management systems, access the data in the database so the program can consult it to answer queries. The records retrieved in answer to questions become information that can be used to make decisions. The computer program used to manage and query a database is known as a database management system (DBMS).



A Database Management System



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

Database information offers many advantages including:

• Increased Flexibility - Databases tend to mirror bsuiness structures, and a good database can handle changes quickly and easily, just as any good business needs to be able to handle changes quickly and easily. Databses provide flexibility in allowing each user to access the information in whatever way best suits their needs.
• Increased Scalability and Performance - Only a database could 'scale' to handle the massive volumes of information and the large numbers of users required for successful launch of the Australian Bureau of Statistics (ABS) website. Scalability refers to how well a system can adapt to increased demands. Performance measures how quickly a system performs a certain process or transaction.
• Reudced Information Redundancy - redundancy is the duplication of information, or storing the same information in multiple places. Redundant information occurs because organisation frequently capture and store the same information in multiple locations.
• Increased Information Integrity (Quality) - information integrity is a measure of the quality of information. Within a database environment, integrity constraints are rules that help ensure the quality of information. Itegrity constraints can be defined and built into the database design. The databse ensure that users can never violate these constraints. There are two types of integrity constraints: (1) relational integrity constraints and (2) business-critical integrity constraints.
• Increased Information Security - As systems become increasingly complex and more available over the internet, security becomes an even bigger issue. Databases offer many security features including passwords, access levels and access controls. Passwords provide authentication of the user who is gaining access to the system. Access levels determine who has access to the different types of information and access controls determine what type of access they have to the information.

4. Define the fundamental concepts of the relational database model.

Entities and Attributes
An entity in the relation database model is a person, place, thing, transaction or event about which information is stored. A table in the relational database model is a collection of similar entities. Attributes, also called fields or columns, are characteristics or properties of an entity class.

Keys and Relationships
to manage and organise various entity classes within the relational database model, developers must identify primary keys and foreign keys and use them to creat logical relationships. A primary key is a field that uniquely identifies a given entity in the table. A foreign key in the relational databas emodel is a primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables.

Example of Database Keys and Relationships

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

Data-driven website business advantages:

• Development - allows the website owner to make changes at any time - all without having to rely on a developer. A well-structure, data-driven website enables updating with little or no training
• Content Management - a static website requires a programmer to make updates. This adds an unnecessary layer between the business and ite web content, which can lead to misunderstandings and slow turnarounds for desired changes.
• Future Expandability - having a data-driven website enables the site to grow faster than would be possible with a static site. Changing the layout, displays and functionality of the site is easier ith data-driven solution.
• Minimising Human Error - Even the most competent programmer can make mistakes, leading to bugs and inconsistencies that can be time consuimg and expensive to track down and fix, A well-designed, data-driven website will have 'error-trapping' mechanisms to ensure that required information is filled out correctly and that content is entrered and displayed in its correct format.
• Cutting production and Update Costs - a data-driven website can be updated and 'published' by any competent data0entry person. In addition to being convenient and more affordable, changes and updates will take a fraction of the time that they would on a static site.
• More Efficient - with a data-driven solution, the system keeps track of the templates, so users do not have to. A data-driven infrasturcture will improve the reliability and stability of a website, while greatly reducing the chance of 'breaking' some part of the site when adding new areas.
• Improved Stability - if a programmer is not organised or leaves unexpectedly, it colud involve recreating existing work if those source files cannot be found. With a data-driven website, there is peace of mind, knowing the content is never loset - even if the programmer is!

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

A Data warehouse is a logical collection of information - gathered from many different operation databases - that supports business analysis activites and decision-making tasks. The primary purpose of a data warehouse is to aggregate informtation throughout an organsisation into a single repository in such a way that employees can make decisions and undertake business analysis activities. A Data mart contains a subset of data warehouse information. To distinguish between data warehouses and data marts, think of data warehouses as having a more organisational focus and data marts having focused information subsets particular to the needs of a given business unit such as finance or production and operations.



A Data Warehouse Overview