Editing First normal form (section)

{{short description|Concept in database normalization}}
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'''First normal form''' ('''1NF''') is the simplest form of [[database normalization]] defined by English computer scientist [[Edgar F. Codd]], the inventor of the [[relational database]]. A [[Relation (database)|relation]] (or a [[Table (database)|''table'']], in [[SQL]]) can be said to be in first normal form if each field is ''atomic'', containing a single value rather than a set of values or a [[nested table]]. In other words, a relation complies with first normal form if no [[attribute domain]] (the set of values allowed in a given column) has relations as elements.<ref>Codd, E. F. (1972). "Further Normalization of the Data Base Relational Model". p. 27</ref>

Most relational database management systems, including standard SQL, do not support creating or using table-valued columns, which means most relational databases will be in first normal form by necessity. Otherwise, normalization to 1NF involves eliminating nested relations by breaking them up into separate relations associated with each other using [[foreign key]]s.<ref name="Codd 1970">{{Cite journal |title=A relational model of data for large shared data banks |journal=Communications of the ACM |last=Codd |first=E. F. |volume=13 |issue=6 |pages=377&ndash;387 |author-link=Edgar F. Codd |year=1970 |doi=10.1145/362384.362685}}</ref>{{rp|pages=381}} This process is a necessary step when moving data from a non-relational (or [[NoSQL]]) database, such as one using a [[hierarchical database|hierarchical]] or [[document-oriented database|document-oriented]] model, to a relational database.

A database must satisfy 1NF to satisfy further "[[Database_normalization#Normal_forms|normal forms]]", such as [[Second normal form|2NF]] and [[Third normal form|3NF]], which enable the reduction of redundancy and anomalies. Other benefits of adopting 1NF include the introduction of increased [[data independence]] and flexibility (including features like [[Many-to-many (data model)|many-to-many]] relationships) and simplification of the [[relational algebra]] and [[query language]] necessary to describe operations on the database.

Codd considered 1NF mandatory for relational databases, while the other normal forms were merely guidelines for database design.<ref>{{Cite journal |title=Extending the database relational model to capture more meaning |journal=ACM Transactions on Database Systems |last=Codd |first=E. F. |volume=4 |issue=4 |pages=397&ndash;434 |author-link=Edgar F. Codd |year=1979 |doi=10.1145/320107.320109}}</ref>{{rp|page=439}}