Unit 4 - Exchanging Data

Understand the difference between lossless and lossy compression

Explain run length encoding and dictionary based compression

Define symmetric and asymmetric encryption

Understand how and why hashing may be used to encrypt data

Explain the concept of a relational database

Define the terms  flat file, entity, attribute, primary key, foreign key, secondary key, entity relationship modelling, referential integrity

Produce an entity relationship model for a simple scenario involving multiple entities

Explain the concept of a relational database

Normalise relations to third normal form

Understand why databases are normalised

Be able to use SQL to retrieve data from multiple tables of a relational database

Be able to interpret and modify SQL

Be able to use SQL to define a database table

Be able to use SQL to update, insert and delete data from multiple tables of a relational database

Describe methods of capturing, selecting, managing and exchanging data

Describe what is meant by transaction processing and ACID (Atomicity, Consistency, Isolation, Durability)

Describe what is meant by record locking and why it is necessary in a multi-user database

Describe what is meant by redundancy