# Data event

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A **data event** is a relevant state transition defined in an event schema.[1] Typically, event schemata are described by pre- and post condition for a single or a set of [data items](/source/Data_item). In contrast to ECA ([Event condition action](/source/Event_condition_action)), which considers an event to be a signal, the data event not only refers to the change (signal), but describes specific state transitions, which are referred to in ECA as conditions.

Considering data events as relevant [data item](/source/Data_item) state transitions allows defining complex event-reaction schemata for a database. Defining data event schemata for [relational databases](/source/Relational_database) is limited to attribute and instance events. [Object-oriented databases](/source/Object-oriented_database) also support collection properties, which allows defining changes in collections as data events, too.

## References

1. Karge, R. (July 2003). [*Unified Database Theory*](http://www.odaba.com/content/downloads/documentation/P1_UnifiedDatabaseTheory.pdf) (PDF document). The 7th World Multi-Conference on SYSTEMICS, CYBERNETICS AND INFORMATICS - SCI 2003.

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