Data Storage Flashcards
Explain the difference between a Field and an Item of data.
A field specifies a data type and has a name. An item is one piece of data that will fit within a field in a record
Why would a foreign key be used in a relational database?
To link the data to a related data in another table
What is SQL?
Structured Query Language allows users to create databases and tables to insert, retrieve and modify data by sending commands to the Database Management System
Advantages of moving from a flat database to a relational database
Data is easier to manipulate and less prone to errors like data duplication and data loss
Disadvantages of moving from a flat database to a relational database
It takes time and requires technical skill to understand and build an effective relational database to move to, which can be expensive for a company
Why is data given set types?
To avoid errors where inappropriate data could be entered and to make data processing easier as it is in the correct form
Give the data types that can store a number
Short, Long, Int, Double, Float
Explain what a Boolean value is and give an example where it may be used.
Either a true or false, used where nothing else is possible. eg: to track if a product has gone out of print in retail business database
What kind of data is most often categorised as “Big Data”?
Personal data collected from tracking or social media
Why do companies and organisations want so much data about you?
To build profiles, which can be used to predict your interest and to effectively market products in a targeted manner
What is the major UK law that keeps data safe?
The GDPR requires organisations to responsibly keep data limited. What they can collect and use, they must be responsive
Examples of different SQL database systems
SQLite, MySQL, Oracle, Microsoft, PostgreSQL
Some services use a “NoSQL” database, how does this differ?
A NoSQL database is an evolution of a flat model that adds constraints to make sure that data is copied to the correct places as it is updated
What advantages does NoSQL offer?
It can be faster to read from than a relational database but compromises consistence as even when data is copied this takes time and queries made during that time may return old data
How are negative numbers stored in binary?
An extra bit may be used which indicates if a number is positive or negative, this will reduce the amount of space available by half, so is only done when negatives are needed
