Data bases and Data warehouses

Week 7 Questions

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

· Accuracy: the extent to which something is accurate e.g. are names spelled correctly?

· Completeness: are values in database compete e.g. is the address fully complete include postcode etc.

· Consistency: are certain types of information in agreement with each other? E.g. total felids equalling true total of individual fields.

· Uniqueness: does information only appear once? E.g. are there any duplicate customers?

· Timelessness: is information current e.g. is it updated on a weekly basis.

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

A database maintains information about various types of objects, event, people and places. While a database management system (DBMS) is a computer program used to manage and query a database.

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

Increased flexibility- good databases can handle changes quickly and easily.

Increase scalability and performance- databases today scale to exceptional levels, allowing all types of users and programs to perform information=processing and information searching tasks.

Reduced information redundancy- this can be achieved by recording each piece of information in only one place in the database.

Increased information integrity- the specification and enforcement of integrity constraints produce higher quality information.

Increased information security- provide security features including; passwords, access levels and access controls.

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

A relational database is a collection of tables from which data can be accessed in many different ways without having to reorganize the database tables.

Database fundamentals include:

· Entities and attributes- an entity in the relational database model is a person, place, thing, transaction or event about which information is stored. While attributes are characteristics or properties of an entity class.

· Keys and relationships- a primary key is a field that uniquely identifies a given entity in a table. While a foreign key is a primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the 2 tables.

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

- Allows the reader to make changes anytime and develop it easily.

- Does not require a programmer to make updates

- Enables the site to grow faster then would be possible with a static site.

- Minimisers human error

- Cuts down production and updating costs

- Efficient at keeping volumes of information intact

- Improved stability

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

A data warehouse is a logical collection of information that supports business analysis activities and decision-making tasks. The main purpose of a data warehouse is to aggregate information throughout an organisation into s 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.