Databases (1.3.1) Flashcards
What is a database?
A persistant, organised store of related data.
What is a relational database?
A database which recognizes the differences between entities by creating different tables for each entity which form a relationship.
What is an entity?
An item of interest that has data stored about it.
What is an attribute?
Characteristics or categories of an entity
What is a flat-file database?
A database with on file/ table usually based around a single entity.
What is a record?
A group of related fields or one instance of an entity.
What is a field?
A single piece of data
What is a primary key?
A unique identifier for each record in a table.
What is a foreign key?
A common attribute which links two tables together.
What is a secondary key?
Another other key which allows a database to be search quickly but is not unique to a single record.
What are the three main ER diagram relationships?
- one to one
- one to many
- many to many
What is a one to one relationship?
When each entity can be linked only one other entity e.g. husband to wife
What is a one to many relationship?
One table is linked to many others e.g. mother to children
What is a many to many relationship?
When one entity can be associated to many other entities and vice versa. e.g. students and lessons.
This is not allowed in a relational database because it leads to redundant data.
How can data be captured?
- Manually
- Magnetic Ink Character Recognition
- Optical mark Recognition
- Optical character recognition
