Wednesday, May 27, 2009

Chapter 4

What are some of the difficulties in managing data?
Difficulties in managing data include:
- Amounts of available data boosts exponentially with time
- Despite the fact that new data is added rapidly, most historic data is kept for a long time causing an even larger build up of data.
- New sources of data emerge.
- Overtime there begins to be data delays
- Data security, quality, and integrity are critical, yet they are easily jeopardised.
- Data can be scattered throughout organisations.

What are the various sources for data?

- Internal Data --> e.g. corporate databases
- External Data --> e.g. commercial databases
- Personal Data --> e.g. personal thoughts, opinions and experiences
- Data also comes from the web in the form of Clickstream data. Clickstream data are those data that visitors and customers produce when they visit a website and click on hyperlinks.

What are a primary key and a secondary key?

Primary key is the identifier field that uniquely identifies a record so that it can be retrieved, updated and sorted. Secondary keys are other fields that have some identifying information but typically do not identify the file with complete accuracy. For example, the students major might be a secondary key if a user wanted to find all students in a particular major field of study.
(primary key shown)

What is an entity and a relationship?

An entity is a person, place, thing, or event about which information is maintained. Entities are associated with one another in relationships, which can include many relationships. The number of entities in a relationship is the degree of relationship.

What are the advantages and disadvantages of relational databases?

An advantage is that this feature allows user’s great flexibility in the variety of queries they can make. A disadvantage is that due to large scales being composed of interrelated tables, the overall design can be complex hence have slow search and access times

What is knowledge management?

Knowledge management is a process that helps organisations identify, select, organise, disseminate, transfer, and apply information and expertise that are part of the organisations memory and that typically reside within the organisation in an unstructured manner.

What is the difference between tacit knowledge and explicit knowledge?

Tacit knowledge is the cumulative store of subjective or experiential learning; highly personal and hard to formalise knowledge. On the other hand explicit knowledge encompasses more objective, rational, and technical knowledge.

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