Databases Flashcards
Define entity
An entity is a category of object, person, event or thing of interest about which data needs to be recorded
What is a flat file?
consists of information about a single entity
1 table
What is a primary key
a unique idetifier for each record
primary keys are underlined
Entity relationships
One-to-one e.g. Husband and Wife
One-to-many e.g. Mother and Child, School and Pupil
Many-to-many e.g. Actor and Film, Recipe and Ingredient
What is a foreign key?
A foreign key is an attribute that creates a join between two tables (relations)
It is the primary key in the first relation
What is a composite primary key?
Two or more attributes that are needed to uniquely identify
Why have databases?
They allow data to be :
retrieved quickly
updated
filtered
What is data integrity?
The maintenance of a state of consistency in a data store
What is data corruption?
The opposite of data intergity
What is data security?
Keeping data safe
