C175 Ch.5

verickle's version from 2017-08-21 20:27

Normal Forms

Question Answer Column 3
First normal form (1NF)Table format, no repeating groups, and PK identifiedConversion To First Normal Form
Second normal form (2NF)1NF and no partial dependenciesConversion To Second Normal Form
Third normal form (3NF)2NF and no transitive dependenciesConversion To Third Normal Form
Boyce-Codd normal form (BCNF)Every determinant is a candidate key (special case of 3NF)The Boyce-Codd Normal Form
Fourth normal form (4NF)3NF and no independent multivalued dependenciesFourth Normal Form (4NF)

Functional Dependence Concepts

Question Answer
Functional dependenceThe attribute B is fully functionally dependent on the attribute A if each value of A determines one and only one value of B.
Functional dependence (generalized definition)Attribute A determines attribute B (that is, B is functionally dependent on A) if all (generalized definition) of the rows in the table that agree in value for attribute A also agree in value for attribute B.
Fully functional dependence (composite key)If attribute B is functionally dependent on a composite key A but not on any subset of that composite key, the attribute B is fully functionally dependent on A.


Question Answer
atomic attributeAn attribute that cannot be further subdivided to produce meaningful components. For example, a person's last name attribute cannot be meaningfully subdivided.
atomicityThe transaction property that requires all parts of a transaction to be treated as a single, indivisible, logical unit of work. All parts of a transaction must be completed or the entire transaction is aborted.
Boyce-Codd normal form (BCNF)A special type of third normal form (3NF) in which every determinant is a candidate key. A table in BCNF must be in 3NF. See also determinant.
denormalizationA process by which a table is changed from a higher-level normal form to a lower-level normal form, usually to increase processing speed. Denormalization potentially yields data anomalies.
dependency diagramA representation of all data dependencies (primary key, partial, or transitive) within a table.
determinantAny attribute in a specific row whose value directly determines other values in that row. See also Boyce-Codd normal form (BCNF).
first normal form (1NF)The first stage in the normalization process. It describes a relation depicted in tabular format, with no repeating groups and a primary key identified. All nonkey attributes in the relation are dependent on the primary key.
fourth normal form (4NF)A table is in 4NF if it is in 3NF and contains no multiple independent sets of multivalued dependencies.
granularityThe level of detail represented by the values stored in a table's row. Data stored at its lowest level of granularity is said to be atomic data.
nonkey attributeSee nonprime attribute.
nonprime attributeAn attribute that is not part of a key.
normalizationA process that assigns attributes to entities so that data redundancies are reduced or eliminated.
partial dependencyA condition in which an attribute is dependent on only a portion (subset) of the primary key.
repeating groupIn a relation, a characteristic describing a group of multiple entries of the same type for a single key attribute occurrence. For example, a car can have multiple colors for its top, interior, bottom, trim, and so on.
second normal form (2NF)The second stage in the normalization process, in which a relation is in 1NF and there are no partial dependencies (dependencies in only part of the primary key).
third normal form (3NF)A table is in 3NF when it is in 2NF and no nonkey attribute is functionally dependent on another nonkey attribute; that is, it cannot include transitive dependencies.
transitive dependencyA condition in which an attribute is dependent on another attribute that is not part of the primary key.