Relational databases/SQL

Question 1

Explain the concept of a database and the different types

Answer 1

A collection of data as tables where they are held together in an organised or logical way

Each complete data entity within a database is called a record (each row) and it is split into certain data categories, these are called the fields (each column) of the record.

The primary key of a database table is a specific column(s) designated to uniquely identify each record. The primary key is copied into other tables as the foreign key

The foreign key is a column(s) used in a relational database to link data between tables and they contain the primary key of a related table

A flat-file database is a database with only one table

A relational database organises data into 2 or more tables which can be linked to one another

Question 2

Why is a database a better storage techniques than file systems?

Answer 2

Data duplication is avoided in databases
Data is also consistent in databases

Question 3

How does a database prevent data duplication

Answer 3

By using a unique primary key field for each record

Question 4

List a few applications of databases

Answer 4

Online shopping lists
Security systems
Social networking sites

Question 5

What is the function of a query language and explain an example

Answer 5

-used to customise and retrieve information from the database
-e.g. Structured Query Language (SQL)