06 Database Systems Flashcards
What is a data warehouse?
A data warehouse is a large collection of archived data from multiple sources used for decision making. Huge quantities of data are stored in a consistent order to make interrogation more productive. In summary, a data warehouse is a huge database specifically structured for information access and reporting.
What is a large collection of archived data from multiple sources used for decision making?
A data warehouse.
What is data mining?
Data mining is the ‘interrogation’ of a data warehouse to help the organisation make decisions. It involves drilling down into the structure of the data to discover meaningful patterns. Users can then identify trends over time and can test theories for accuracy.
What is the ‘interrogation’ of a data warehouse to help the organisation make decisions?
Data mining.
Name advantages to a company of using a data warehouse? (Advantages are similar to data mining)
- Helps identify a list of customers likely to buy a certain product, which they can then use to target with a mail shot.
- The organisation can make comparisons with competitors.
- Can run ‘what if’ queries for modelling exercises.
- Can predict future sales
- Can find the best locations for new shops
- Can analyse sales patterns
- Test analysis of results for plausibility
- Can create reports to help decision making
What is data independence?
Data should be independent of the underlying database structure, for example, if a business has an application for them without having to change the structure or relationships between data tables.
What is data redundancy?
Data is redundant when it is duplicated unnecessarily. I.e. a customer’s address should only be stored in one place, so it can be updated easily.
Data should be independent of the underlying database structure is known as what?
Data independence
Data is redundant when it is duplicated unnecessarily is known as what?
Data redundancy
What is data consistency?
Data must be consistence as it moves from input to processing to output, for instance, if the designer decides the date should be in the format 12/04/18, it shouldn’t sometimes appear as 12th April 2018.
Data must be consistence as it moves from input to processing to output is known as what?
Data consistency
What is data integrity?
Data integrity is the correctness of data. If the value is updated in one place, it should be the same updated value that appears in all the applications built on top of that database.
What is the correctness of data?
Data integrity.
A hospital unit uses a relational database. A patient is allocated to a ward and to a physiotherapist. One table in this database is structured as follows: tblWard (WardID, WardName, Capacity, FreeBeds) Name two other tables you could expect to see in this database.
Would be something like:
tblpatient (patientID[underlined], firstname, surname, dateofbirth, bloodtype, address, nextofkin, wardID, physioID)
tblphysio (psysioID[underlined], firstname, surname, phone)
What is a distributed database?
A distributed database has data stored on a number of computers at different locations, but appears as one logical database to the user. Users can then access data as if it were held centrally in a single source.
What has data stored on a number of computers at different locations, but appears as one logical database to the user?
A distributed database.
List advantages of a relational database over a flat file spreadsheet approach.
- Data will be stored in one place and not be redundant. For example, the customers phone number will only be stored in one field of one table.
- Data will be independent of the database structure, for example, you could create an application for a shop for entering their sales using the same data tables they already use for marketing.
- Data will be consistent from input to processing to output, so dates should always remain in the same format like DD/MM/YY.
- Data is more secure because you can set different access levels for different users, so, a receptionist would be able to see some of the data, whereas a manager would be able to see all of it.
Helps identify a list of customers likely to buy a certain product, which they can then use to target with a mail shot is an advantage of what?
A data warehouse.
The organisation can make comparisons with competitors is an advantage of what?
A data warehouse.