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15 Cards in this Set
- Front
- Back
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What is an entity? |
Name of a table (example “patient” table) |
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What is a tuple? |
A single row of a table |
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What is an attribute? |
A column in a table |
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What is a domain? |
The name of a column |
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What is a child entity? |
When an entity’s lifecycle is entirely dependant on another entity |
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What is entity integrity |
Entity integrity requires every base relation to have a primary key |
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What is referential integrity |
A foreign key must have a matching primary key or it must be null |
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What is a strong entity? |
An entity that exists independently to others (a table without a foreign key or foreign key can be null) |
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What is a composite attribute? |
The attributes can be broken down into meaningful component parts such as address |
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What is a multivalued attribute? |
Attributes that have a set of values for each occurrence of an entity type |
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What are derived attributes? |
Attributes that contain values calculated from the value of related attributes |
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What is a unary relationship |
Relationships exist between instances of the same entity set |
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What is a binary relationship |
Where there is a relationship between two entities |
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What is normalisation? |
A design technique that begins by examining the relationships between attributes and then decompose tables to eliminate redundancy |
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What is the goal of normalisation? |
Minimise data redundancy Simplify data maintenance Simplify enforcement of referential integrity constraints |
