Database Systems Flashcards
What is a Relational database?
A large collection of data items and links between them (1)
With the use of primary and foreign keys (1)
What four problems are associated with flat files?
Data consistency
Data redundancy
Data integrity
Data independence
What is data consistency?
Using one file to hold a central pool of data
A company may hold all its customer details on one file
What is data redundancy?
When data is stored more than once
It refers to the unnecessary duplication of data
What is data integrity?
It is the correctness of data - the extent to which it truthfully represents the original data
What is data independence?
It is when new systems can be developed to access existing data without having to change the data
What is data normalisation?
It is a staged mathematical process (1)
Which removes repeated groups of data & inconsistencies (1)
What is a distributed database?
It has data stored on a number of computers at different locations but appears as one logical database
What is a database management system?
A DBMS is a software used to setup a db ie (Microsoft)
It holds the relationships between data and allows for data to be interrogated
Give three reasons with examples why relational databases are more secure than flat files
Hierarchy of passwords limits users to various parts of the program eg. A receptionist would only have access to basic patient details where as doctors would be able to see all of it
Access rights to parts of the program allow only certain users access and the ability to change data eg. Nurse could see patient detains but only doctor could change them
Data consistency is using one file to hold a central pool of data eg. A company may hold all its customer data on one file
What is data warehousing?
When large amounts of data are stored together in a single location for further processing
Stored in a consistent order
Used to support organisational decision making
What is data mining?
The interrogation of large amounts of data warehouse to discover patterns, trends and possible links between items of data
Uses complex algorithms to search for the patterns
If data is if value It can be processed into a report to aid decision making
Name three advantages of Distributed Computing.
Not dependent on one central store
If one server fails then others can be used
Easy to back up data from one server to another
Name three disadvantages of Distributed Computing.
Security issues - if sensitive data is being transferred may be at risk from hackers
If one server fails no data can be obtained form it
Communication lines are expensive
Name an example of data mining
Fighting shoplifting in clothing stores - Jaeger used data management to look at transactions and position of item in store - found that most items where stolen form near doors - led to increased CCTV, more prosecutions and recovery of goods
