Editing First normal form (section)

== Rationale and drawbacks ==
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Normalization to 1NF is the major theoretical component of transferring a database to the [[relational model]]. Use of a relational database in 1NF brings certain advantages:

* It enables data to be stored in regular [[two-dimensional array]]s; supporting nested relations would require more complex data structures.{{r|Codd 1970}}{{rp|page=381}}
* It allows for the use of a simpler [[query language]], like [[SQL]], since any data item can be identified using only a relation name, attribute name and key; addressing nested data items would require a more complex language with support for hierarchical data paths.
* Representing relationships using foreign keys is more flexible and allows for features such as [[Many-to-many (data model)|many-to-many]] relationships, while a hierarchical model can represent only [[One-to-one (data model)|one-to-one]] or [[One-to-many (data model)|one-to-many]] relationships.
* Since locating data items is not coupled to a parent–child hierarchy, a database in 1NF creates greater [[data independence]] and is more resilient to structural changes over time.{{Clarify|date=May 2025}}
* From 1NF, further normalization becomes possible (for example to [[Second normal form|2NF]] or [[Third normal form|3NF]]), which can reduce data redundancy and anomalies.

The use of 1NF also comes with certain drawbacks:
* Performance worsens for certain operations. In a hierarchical model, nested records are physically stored after the parent record, which means a whole subtree can be retrieved in a single read operation. In 1NF, this will require a join operation per record type, which can be costly, especially for complex trees. For this reason, [[document-oriented database]]s eschew 1NF.
* [[Object-oriented language]]s represent runtime state as trees or [[directed graph]]s of objects connected by [[Pointer (computer programming)|pointers]] or references. This does not map cleanly to a 1NF relational database, creating a gap sometimes called the [[object–relational impedance mismatch]], which [[object–relational mapping]] (ORM) libraries try to bridge.
* 1NF has been interpreted as not allowing complex data types for values. This is open to interpretation though, and [[Christopher J. Date]] has argued that values can be arbitrarily complex objects.{{citation-needed|date=June 2023}}