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20 Cards in this Set
- Front
- Back
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PrimaryKey |
›Anattribute whose value is unique across all occurrences of a relation |
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Relation |
›A named, two-dimensional table ofdata. Each relation consists of a set ofnamed columns and an arbitrary number of unnamed rows |
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Well-StructuredRelation |
›Arelation that contains a minimum amount of redundancy and allows users toinsert, modify, and delete the rows without errors or inconsistencies |
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Normalization |
Theprocess of converting complex data structures into simple, stable datastructures |
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SecondNormal Form (2NF) |
›Eachnonprimary key attribute is identified by the whole key (called full functional dependency) |
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ThirdNormal Form (3NF) |
›Nonprimarykey attributes do not depend on each other (called transitive dependencies) |
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FunctionalDependency |
›Aparticular relationship between two attributes. For a given relation, attribute B is functionally dependent on attributeA if, for every valid value of A, that value of A uniquely determines the valueof B. |
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ForeignKey |
›Anattribute that appears as a nonprimary key attribute in one relation and as aprimary key attribute (or part of a primary key) in another relation |
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ReferentialIntegrity |
›Anintegrity constraint specifying that the value (or existence) of an attributein one relation depends on the value (or existence) of the same attribute inanother relation |
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Field |
The smallest unit of named application data recognized by system software
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Data Type |
A coding scheme recognized by system software for representing organizational data |
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Default Value |
A value a field will assume unless an explicit value is entered for that field |
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Input Mask |
A pattern of codes that restricts the width and possible values for each position of a field |
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Range Control |
Limits range of values that can be entered into field |
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Referential Integrity |
An integrity constraint specifying that the value (or existence) of an attribute in one relation depends on the value (or existence) of the same attribute in another relation |
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Null Value |
A special field value, distinct from 0, blank or any other value, that indicates that the value for the field is missing or otherwise unknown |
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Physical Table |
A named set of rows and columns that specifies the fields in each row of the table |
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Denormalization |
The process of splitting or combining normalized relations into physical tables based on affinity of use of rows and fields |
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Physical File |
A named set of table rows stored in a contiguous section of secondary memory |
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File Organization |
A technique for physically arranging the records of a file |
