# Data item

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{{Distinguish|data point}}
A '''data item''' describes an atomic state of a particular object concerning a specific property at a certain time point.<ref>{{cite web |url=http://www1.unece.org/stat/platform/download/attachments/14319930/Neuchatel+Model+V1.pdf?version=1 |title=Neuchâtel Terminology Model PART II: Variables and related concepts |access-date=2010-08-26 |archive-date=2012-03-05 |archive-url=https://web.archive.org/web/20120305234809/http://www1.unece.org/stat/platform/download/attachments/14319930/Neuchatel+Model+V1.pdf?version=1 |url-status=dead }}</ref><ref>{{cite conference
| url = http://www.odaba.com/content/downloads/documentation/P1_UnifiedDatabaseTheory.pdf
| title = Unified Database Theory
| first = R.
| last = Karge
|date=July 2003
| conference = The 7th World Multi-Conference on SYSTEMICS, CYBERNETICS AND INFORMATICS - SCI 2003
| conference-url = https://lists.cs.columbia.edu/pipermail/tccc/2002-October/000467.html
| location      = Orlando, Florida (USA)
}}</ref> A collection of data items for the same object at the same time forms an object instance (or table row). Any type of complex information can be broken down to elementary data items (atomic state). Data items are identified by [object](/source/Object_(computer_science)) (o), [property](/source/property) (p) and [time](/source/time) (t), while the value (v) is a function of o, p and t: '''v = F(o,p,t)'''.

Values typically are represented by [symbols](/source/symbols) like numbers, texts, images, sounds or videos. Values are not necessarily atomic. A value's complexity depends on the complexity of the property and time component.

When looking at databases or XML files, the object is usually identified by an object name or other type of [object identifier](/source/object_identifier), which is part of the "data". Properties are defined as columns (table row), properties (object instance) or tags (XML). Often, time is not explicitly expressed and is an attribute applying to the complete data set. Other data collections provide time on the instance level ([time series](/source/time_series)), column level, or even attribute/property level.

== References ==
<!--- See Wikipedia:Footnotes on how to create references using <ref></ref> tags which will then appear here automatically -->
{{Reflist}}

Category:Databases
Category:Database theory

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Adapted from the Wikipedia article [Data item](https://en.wikipedia.org/wiki/Data_item) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Data_item?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.