Chapter Six - Databases and Data Warehouses

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

5 characteristics of high quality information:

1. Accuracy: The database needs to have the correct information. Example is the first and last names are spelt correctly.
2. Completeness. In order to use the full capability of the database all necessary information is needed. An example of this is that the full address is complete, that is it includes street, city, state and postcode.
3. Consistency: Is the aggregate or summary information in agreement with detailed information? Example, do all total fields equal the true total of the individual fields?
4. Uniqueness: Is each transaction, entity and event represented only once in the information? for example, are there any duplicate customers?
5. Timeliness:  Is the information current with respect to the business requirements? For example, is information updated weekly, daily or hourly?

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

A database maintains information about various object (inventory), events (transactions), people (employees) and places (warehouses). While a Database Management System is the computer program used to manage and query a database. It is used to access information from a database. Without a database there is no database management systems.

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

From a business perspective, database offers many advantages, including:

• Increased flexibility: A good database can handle changes quickly and easily. Also a database provides flexibility in allowing each user to access information in whatever way best suits his or her needs.
• Increased scalability and performance: Scalability  refers to how well a system can adapt to increased demands while performance measures how quickly a system performs a certain process or transaction. It is only that of a database that can handle the volume of information and the number of users required.
• Reduced information redundancy: Redundancy is the duplication of information, or storing the same information in multiple places. Redundant information occurs because organisations frequently capture an store the information in multiple locations.
• Increased information integrity: 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.
• Increased information security: An organisation must protect the information from any unauthorised users or misuse.

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

Relational database model is a type of database that stores information in the form of logically related rows and columns. The fundamental concepts of relational database model are:

1. Entities and Attributes: An entity is a person, place, thing, transaction or event about which information is stored. Attributes also called fields or columns, are characteristics or properties of an entity class.
2. Keys and relationships: To manage and organise various entity classes within the relational database model, developers must identify keys and create a relationship between them. There are two types of keys  that exist, they are:

• Primary keys: A field (or group of fields) that uniquely identify a given entity in a table.
• Foreign keys: 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.

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

A data base driven website is an interactive website kept constantly updated and relevant to the needs of its customers through the use of a database. The benefits of having a data driven website is:

• Development: Allows website owner to make changes any time with little or even without the need of any help.
• Content Management: A statics website requires a programmer to make updates.
• Future Expandability: Enables site to grow faster. Which is hardly possible with a static site.
• Minimising Human Error: Data driven website contains 'error-trapping' mechanism to ensure that required information is filtered out correctly and information can be entered correctly.
• Cutting Production and Update Costs: It can be updated and published by any competent data-entry or administrative person.  Changes and update takes a fraction of the time of a static site.
• More Efficient: System keeps track of templates so users don't have to. Changes made once, in one place can take care of propagating those changes to the appropriate pages and areas.
• Improved Stability: Any programmer who has to update a website from static templates must be very organised to keep track of all the sources files.