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22 Cards in this Set
- Front
- Back
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alternate key |
A candidate key that was not chosen to be the primary key |
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Boyce-Codd normal form (BCNF) |
A relation is in Boyce-Codd normal form if it is in second normal form and the only determinants it contains are candidate keys; also called third normal form. |
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candidate key |
A minimal collection of columns (attributes) in a table on which all columns are functionally dependent but that has not necessarily been chosen as the primary key. |
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concatenation |
The combination of two or more rows in an operation, such as join, or the combination of two or more columns for a primary key field to uniquely identify a given row in the table. |
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dependency diagram |
A diagram that indicates the dependencies among the columns in a table. |
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first normal form (1NF) |
A table is in first normal form if it does not contain a repeating group. |
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fourth normal form (4NF) |
A table is in fourth normal form if it is in third normal form and there are no multivalued dependencies. |
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functionally dependent |
Column B is functionally dependent on column A (or on a collection of columns) if a value for A determines a single value for B at any one time. |
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functionally determines |
Column A functionally determines column B if B is functionally dependent of A. |
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interrelation constraint |
A constraint that involves more than one relation. |
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multidependent |
In a table with columns A, B, and C, B is multidependent on A if each value for A is associated with a specific collection of values for B and, further, this collection is independent of any values for C. |
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multidertermine |
In a table with columns A, B, and C, A multidetermines B if each value for A is associated with a specific collection of values for B and further, this collection is independent of any values for C. |
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multivalued dependence |
In a table with columns A, B, and C, there is a multivalued dependence of column B on column A (also read as "B is multidependent on A" or "A multidetermines B"), if each value for A is associated with a specific collection of values for B and, furthermore, this collection is independent of any values for C. |
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nonkey column |
An attribute (column) that is not part of the primary key. |
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normalization process |
The process of removing repeating groups to produce a first normal form table. Sometimes refers to the process of creating a third normal form table. |
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partial dependency |
A dependency of a column on only a portion of the primary key. |
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primary key |
A minimal collection of column (attributes) in a table on which all columns are functionally dependent and that is chosen as the main direct-access vehicle to individual rows. |
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repeating group |
More than one entry at a single location in the table. |
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second normal form (2NF) |
A relation is in second normal form if it is in first normal form and no nonkey attribute is dependent on only a portion of the primary key. |
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third normal form (3NF) |
A table is in third normal form if it is in second normal form and the only determinants it contains are candidate keys. |
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unnormalized relation |
A structure that satisfies the properties required to be a relation (table) with the exception of allowing repeating groups (the entries in the table do not have to be single-valued). |
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update anomaly |
An update problem that can occur in a database as a result of a faulty design. |
