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- Q4165818 subject Q8363908.
- Q4165818 abstract "Domain-key normal form (DK/NF) is a normal form used in database normalization which requires that the database contains no constraints other than domain constraints and key constraints.A domain constraint specifies the permissible values for a given attribute, while a key constraint specifies the attributes that uniquely identify a row in a given table.The domain/key normal form is achieved when every constraint on the relation is a logical consequence of the definition of keys and domains, and enforcing key and domain restraints and conditions causes all constraints to be met. Thus, it avoids all non-temporal anomalies.The reason to use domain/key normal form is to avoid having general constraints in the database that are not clear domain or key constraints. Most databases can easily test domain and key constraints on attributes. General constraints however would normally require special database programming in the form of stored procedures that are expensive to maintain and expensive for the database to execute. Therefore, general constraints are split into domain and key constraints.It's much easier to build a database in domain/key normal form than it is to convert lesser databases which may contain numerous anomalies. However, successfully building a domain/key normal form database remains a difficult task, even for experienced database programmers. Thus, while the domain/key normal form eliminates the problems found in most databases, it tends to be the most costly normal form to achieve. However, failing to achieve the domain/key normal form may carry long-term, hidden costs due to anomalies which appear in databases adhering only to lower normal forms over time.The third normal form, Boyce–Codd normal form, fourth normal form and fifth normal form are special cases of the domain/key normal form. All have either functional, multi-valued or join dependencies that can be converted into (super)keys. The domains on those normal forms were unconstrained so all domain constraints are satisfied. However, transforming a higher normal form into domain/key normal form is not always a dependency-preserving transformation and therefore not always possible.".
- Q4165818 wikiPageExternalLink intro-to-normalization.html.
- Q4165818 wikiPageExternalLink normalization.htm.
- Q4165818 wikiPageExternalLink nf3.
- Q4165818 wikiPageExternalLink 283878.
- Q4165818 wikiPageExternalLink tods81.pdf.
- Q4165818 wikiPageExternalLink rm7.html.
- Q4165818 wikiPageWikiLink Q1508721.
- Q4165818 wikiPageWikiLink Q2385774.
- Q4165818 wikiPageWikiLink Q2460153.
- Q4165818 wikiPageWikiLink Q2492241.
- Q4165818 wikiPageWikiLink Q2492261.
- Q4165818 wikiPageWikiLink Q311585.
- Q4165818 wikiPageWikiLink Q339072.
- Q4165818 wikiPageWikiLink Q374182.
- Q4165818 wikiPageWikiLink Q8363908.
- Q4165818 comment "Domain-key normal form (DK/NF) is a normal form used in database normalization which requires that the database contains no constraints other than domain constraints and key constraints.A domain constraint specifies the permissible values for a given attribute, while a key constraint specifies the attributes that uniquely identify a row in a given table.The domain/key normal form is achieved when every constraint on the relation is a logical consequence of the definition of keys and domains, and enforcing key and domain restraints and conditions causes all constraints to be met. ".
- Q4165818 label "Domain-key normal form".