Data Normalisation (OCR A-Level Computer Science): Flashcards
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Practise the cards
13 cards from this deck
Data Normalisation purpose
Data Normalisation purpose
Organise data, minimise redundancy, improve data integrity
Three most common Normal Forms
Three most common Normal Forms
1NF, 2NF, 3NF
1NF: Type of values required in fields
1NF: Type of values required in fields
Atomic (indivisible) values
1NF: Required unique identifier
1NF: Required unique identifier
Primary key
1NF: What must be eliminated
1NF: What must be eliminated
Repeating groups of data
2NF: What dependencies must be removed
2NF: What dependencies must be removed
Partial dependencies
2NF: Type of key it applies to
2NF: Type of key it applies to
Composite primary keys
3NF: What dependencies must be removed
3NF: What dependencies must be removed
Transitive dependencies
Atomic values meaning
Atomic values meaning
Indivisible values
Composite primary key definition
Composite primary key definition
Primary key with multiple fields
Partial dependency definition
Partial dependency definition
Non-key attribute depends on part of composite key
Transitive dependency definition
Transitive dependency definition
Non-key attribute depends on another non-key attribute
Benefit: Normalisation effect on redundancy
Benefit: Normalisation effect on redundancy
Reduces redundancy, minimises storage costs