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In [[Temporal database|temporal database]]s, '''transaction time''' (TT) is the time during which a fact stored in the database is considered to be true. As of December 2011, ISO/IEC 9075, Database Language [[SQL:2011|2011]] Part 2: SQL/Foundation included clauses in table definitions to define "system-versioned tables" (that is, transaction-time tables).

In a database table transaction interval is often represented as an interval allowing the system to "remove" entries by using two table-columns ''StartTT'' and ''EndTT''. The time interval is closed at its lower bound and open at its upper bound.<ref>Kedar, S. V. (2013). Database management systems. Pune, India: Technical Publications.</ref>

When the ending transaction time is unknown, it may be considered as "Until Changed".  Academic researchers and some RDBMS have represented "Until Changed" with the largest timestamp supported or the keyword "forever".  This convention is not technically precise.

The term was coined by [[Biography:Richard T. Snodgrass|Richard T. Snodgrass]] and his doctoral student Ilsoo Ahn.<ref>{{Cite journal | last1 = Snodgrass | last2 = Ilsoo Ahn | title = Temporal Databases | journal = Computer | volume = 19 | issue = 9 | pages = 35 | year = 1986 | doi = 10.1109/MC.1986.1663327| url = http://www2.cs.arizona.edu/~rts/pubs/Computer.pdf }}</ref>

==See also==
* [[Software:Valid time|Valid time]]
* [[Software:Decision time|Decision time]]
* [[Temporal database#Using transaction time|Using transaction time]]

==References==
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[[Category:Database management systems]]
[[Category:Transaction processing]]


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