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Unit 4

  • 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 for a multi-user database

  • Describe what is meant by redundancy

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