Database Concepts - OCR Computer Science A Level

Question	Answer
What is an Entity?	A category of object, person, event, or thing of interest to an organisation, about which data is to be recorded
What are Attributes and Records?	> Attributes - columns of the whole table (entity) > Records - rows of the whole table
What is a Flat File Database?	> Consists of a single file > Suitable to store one entity, e.g., a list of aname > Repeated data makes them inefficient > Unsuitable for more than one entity and their relationships
What is a Primary Key?	> Identifyer required for each entity in a database > Usually a numeric key for each record
What is a Secondary Key?	Used as an alternative index that is easier to know, e.g., a surname rather than a number
What are the 3 Types of Relationships between Entities?	> One-to-One > One-to-Many > Many-to-One
What is a Foreign Key?	> Attribute that joins two tables > Common to both tables - primary key in one, foreign in another > Allows for relationships between tables
How are Tables Linked in Many-to-Many Relationships?	> Additional table is created, containing just both primary / foreign keys > Both keys in the one table count as a "composite primary key"
What is Referential Integrity?	> Keeping shared / required attributes in databases > Shared attributes are not deleted on only one entity, in order to maintain the relationship

Resource summary

	Created by Malachy Moran-Tun almost 3 years ago

	Copied by Malachy Moran-Tun almost 3 years ago