Flashcards
SCC 201 - Normalisation - First Normal Form
Cards in this deck (13)
- 1What is normalization?A process which takes a relation schema through a series of tests to certify whether it satisfies a certain normal form
- 2What are the two requirements of first normal form?– The domain of an attribute must include only atomic values
– The value of any attribute in a tuple must be a single value from the domain of that attribute - 3What does first normal form disallow, include the term "relations"?Disallows multi-valued attributes, composite attributes and their combinations
– An attribute value for a single tuple cannot be a set of values, a tuple of values or a combination of both
– No nested relations - 4Describe the first normal form first solution and what is it known as?Remove the attribute that violates 1NF in relation R1
• Place it in a separate relation R2 along with the primary key from R1
• This is known as primary key propagation - 5Describe the first normal form second solution technique?• Expand key so there will be a separate tuple in original relation for each value of multi-valued/ composite attribute
- 6Disadvantage of 1 normal form: solution technique 2?Introduces redundancy due to duplication and also increase space needed to store data.
- 7Describe the first normal form solution technique 3?If maximum number of values n is known for multi-valued attribute, replace it by n atomic attributes
- 8What an data redundancy lead to?Data redundancy leads to data anomalies and corruption.
- 9—
- 10State the disadvantage of 1 NF: solution technique 3?Has disadvantage of introducing NULL values if departments have fewer than three locations
- 11Which solution technique is better?Solution technique 1 is better
-Does not suffer from redundancy
– No limit placed on maximum number of values - 12What would happen if the second solution is chosen?If second solution is chosen it will be
decomposed into first solution during
subsequent normalization steps - 13What are sub trees after the first normal form solution?Sub-trees are the name given to the chopped of relational attributes from first normal form - solution 1
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- Flashcards on SCC 201 - Normalisation - First Normal Form, created by Ayo Olutobi on 29/03/2017.
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- Ayo Olutobi
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