Databases - paper 1 Flashcards
What are the features of a relational database?
Created of 2 or more entities
An entity is an item of interest that information is stored about
What is an entity relationship model?
Shows two or entities and how they link
What is an attribute?
Characteristics of an entity
What is a flat file database?
A database that consists of a single file.
One single entity and its attributes
What is a primary key?
A unique identifier for each record in a table
Shown by a line underneath it in an entity relationship model
What is a foreign key?
A foreign key is an attribute that links two or more tables together.
The foreign key will be the primary key in one table and a foreign key in another
What is a secondary key?
A secondary key allows databases to be searched quickly e.g if the patient ID is the primary key the secondary key may be their surname as it is easier to remember
What are the different types of entity relationship models?
One to one
One to many
Many to many
What is normalisation?
Coming up with the best possible design for a database
What is transaction processing?
A single logical operation is called a transaction
What is a hash table?
A table with a set of values after they have gone through a hash function.
What is dictionary compression?
Creating a table of reoccurring words or phrases to save space
What is commitment ordering
priorities transactions based on the dependencies on one another in addition to time
