Databases Flashcards
What is a flat file database?
A flat file database is a simple database that stores all data in a single file or table. It contains related and unrelated data. A flat file database can be stored in a text, a spreadsheet or in a database file that contains one or more unrelated data.
What is meant by a relational database?
Groups of tables linked together by primary and foreign keys.
Describe the advantages of a relational database approach over a flat file approach?
- (Security) HIERARCHY OF PASSWORDS - limits users to various parts of the program for example a receptionist would only have access to basic computer details whilst the manager would see all information on the customer account.
- (Security) access rights to parts of the program only certain users can access and change data. For example, a clerk would see all the information on a customer account but be unable to alter the hire rate details whilst a manager could.
- CONSISTENCY - Data consistency is the relationship between the input data, the processed data and the output data as well as other related data.
- Redundancy -data redundancy is where you store and item of data more than once.
- Independence - Data independence - The data and the applications/programs used to access it are independent/separate.
What is normalisation?
Normalisation is the process undertaken to ensure that a database has no redundant or inconsistent data.
Definition of a database
A database is an organised collection of related data.
What is definition of data consistency?
Data consistency is where the same data has exactly the same value and formatting throughout.
What is the definition of data redundancy?
Data redundancy is where you store an item of data more than once.
What is the definition of data integrity?
Data integrity is the correctness of the data. Truthful, accuracy.
What is the definition of data independence?
Date independence is the data and applications/programs used to access it are independent/separate.
What is a data warehouse and give an example of how a company might use it?
Data warehouse is a large collection of archived data used for decision-making. Example includes-allows the company to store information about every sale and allows the company to use data mining.
Explain what is meant by data mining and give a detailed example of how a company might use it?
Data mining is interrogating the data to find patterns in the data which is stored in the warehouse. For example comparisons with competitors, predictions for future sales and analysing buying patterns.
What is the definition of data normalisation?
Data normalisation is the staged (mathematical) process of removing repeated groups of data and inconsistencies.
Two reasons why relational database is more secure than the flatfile approach?
They allow hierarchy of the passwords and access rights to certain part of the systems.
Define what is meant by distributed database ?
Distributed databases is when data is stored in number of computers located in different locations however is shown as one logical database.
