1.7 Database Systems Flashcards
Give three examples of standard relational databases:
Microsoft SQL server
Oracle Database
MYSQL
Advantages to relational database systems:
The ability to create meaningful information by joining the tables
Simple explanation on relational databases
There are multiple small tables of data linked to each other to reduce repeating of data
What is a relational database
It is a collection of information that organises data in predefined relationships where data is stored in one or more tables of columns and rows
What is a database?
It Is a data structure that can hold vast amounts of data in a way that makes it easy to modify and search.
In a flat file database information is held in …
A single table.
Each column in a flat file database is called an … and each row is called a …
Attribute
Record
Flat File databases are generally used for …
Small amounts of data
Foreign Key
Is the field that links to the primary key in another table
Primary Key
Is A unique identifier in a table for a row
What are the three kinds of entity relationship diagrams?
One-to-one
One-to-many
Many-to-many
What is an entity relationship diagram?
It is a simple diagram of a relational database
Can many-to-many links exist?
No, They must be removed during normalisation
How do you draw links?
They are straight lines, with crows feet on one of the ends to represent the many part of the relationship
Give an example of a one-to-many relationship:
Owner to car. Each owner may own multiple cars but each car can only have one owner
