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First normal form (1NF) is a property of a relation in a relational database. A relation is in first normal form if the domain of each attribute contains only atomic values, and the value of each attribute contains only a single value from that domain. Edgar Codd, in a 1971 conference paper, defined a relation in first normal form to be one such that none of the domains of that relation should have elements which are themselves sets. First normal form is an essential property of a relation in a relational database. Database normalization is the process of representing a database in terms of relations in standard normal forms, where first normal is a minimal requirement. First normal form enforces these criteria: *Eliminate repeating groups in individual tables. *Create a separate table for each set of related data. *Identify each set of related data with a primary key ==Examples== The following scenario illustrates how a database design might violate first normal form.〔(studytonight.com )〕〔(stackoverflow.com )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「First normal form」の詳細全文を読む スポンサード リンク
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