(10) Fundamentals of Databases Flashcards
What is normalisation?
The process of ensuring that a database is designed in its most efficient form
What is 0NF?
A table with no normalisation, all data and fields in one table.
What is 1st Normal form?
Doesn’t contain repeating attributes and all values cant be broken into separate parts
What is 2nd Normal form?
Same as 1st but contains no partial key dependency
What is 3rd Normal form?
Same as 2nd Normal form but it contains no non key dependency
What is a database?
A collection of data in an organised and logical way
What are the 4 types of relationships in relational databases?
One to One
One to Many
Many to One
Many to Many
What is a relational database?
A collection of tables in which relationships are modelled by shared attributes
What is are attributes?
Describing characteristics of an object in a database
What is a primary key?
An attribute that can uniquely identify a row
What is a composite primary key?
An attribute that can be used to uniquely identify every record within a table
What is a foreign key?
An attribute in a table that is a primary key in another table and is used to link tables
Why are databases normalised?
To allow the database to be as efficient as possible by reducing the amount of redundancies (repeated data)
What is SQL?
A text based querying system. Used by a lot of relational databases
What are the two parts of SQL and what are they?
DDL - Used to create database tables
DML - Used to retrieve, Update, Insert and delete data in a database
