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Computer Science

GCSE · AQA

QuestionsFlashcards

Cyber Security Threats
Social Engineering
- What Social Engineering Is
  4
- Blagging, Phishing & Shouldering
  5
Malware
- What Malware Is
  2
- Viruses, Trojans & Spyware
  3
Detecting & Preventing Threats

Data Inconsistency & Redundancy Flashcards

All 5 cards in this deck

What is data redundancy?: The same data being stored more than once, unnecessarily, e.g. a customer's address repeated on every one of their orders.
What is data inconsistency?: When the same data is stored in more than one place but the copies are not identical, e.g. an address changed in one record but not in the others.
How does a relational database reduce data redundancy?: Each item of data is stored once, in one table. Other tables refer to it using a foreign key instead of repeating it.
How does a relational database reduce data inconsistency?: Because each item of data is stored only once, a change is made in one place, so no out-of-date copies are left to disagree with it.
Apart from keeping data consistent, what is one other benefit of removing data redundancy?: The database takes up less storage space, because each item of data is stored once instead of being repeated.