Chapter 5 - Relational Database Concepts Flashcards
What is duplicate data?
Data that exists in two tables
What does referential integrity ensure?
That is impossible to enter a reference in your database to a link that doesn’t exist
What is an attribute?
An characteristics of an entity
What is an entity
A real world object
What is a foreign key?
A primary key in another table
What is a primary key?
An unique identifier
What is second normal form?
The table must be in first normal form and all of the non key attributes must be dependent on the primary key
What is the third normal form?
The table must already be in second normal form and all non-key attributes must be formally dependent on the primary key
What is first normal form?
Each table must have a primary key, each field name is unique, there are no repeating fields in a single record and all data within a field must be atomic
What does a data dictionary contain?
Details of all the entities and attributes
What is normalisation?
The process of refining a datamodel
What is a parameter?
A value used by a query to select records
What is a composite key?
Primary key with more than one field
