INFS601 Revision

A database is an organised collection of data that has been organised to model relevant aspects of reality in a way that supports processes requiring this information.

Information is data that is processed and had context added to reveal it's meaning. In order for information to be used for decision making it must be accurate, timely and relevant

Raw fact that are of interest to end users

Data about data

Provides a description of data characteristics and relationships in the data in such a way that complements and expands the value of the data

A database management system is a collection of programs that manages the structure of the database and controls access to data storage and modification and the extraction of information

• Data redundancy
• Data inconsistency
• Data anomalies
• Lengthy development times
• Difficulty getting quick answers to questions
• Complex administration
• Lack of security leading to limited data sharing
• Extensive programming

Data redundancy occurs when the same data is stored in different places.

Different, conflicting versions of the same data in different places

Data anomalies are anomalies that result from all changes in redundant data not being made correctly.

Structural dependence occurs when access to a file is dependant on it's own structure. Structural independence occurs when a file's structure can be changed without affecting access to it's data.

Data dependence occurs when access to data changes when data characteristics change. Data independence occurs when changes to data characteristics do not effect access to data.

The database management system:

• Acts as an intermediary between the user and the database
• Enables data to be shared
• Integrates many users views of the data
• Receives and translates application requests into the operations required to fulfil the requests
• Hides internal complexity from programmes and users

The process of transforming a conceptual data model into a logical one which is consistent and compatible with a specific type of database technology.

1. Data dictionary management
2. Data storage management
3. Data transformation and presentation
4. Security management
5. Multi-user management
6. Backup and recovery management
7. Data integrity management
8. Provides database access languages and application programming interfaces
9. Provides database communication interfaces