# Trivial join dependency

**URL:** <https://forums.unrealengine.com/t/trivial-join-dependency/649355>\
**Category:** Tutorial & Course Discussions\
**Tags:** database, unreal-engine\
**Created:** [September 15, 2022, 12:22pm UTC](https://forums.unrealengine.com/t/trivial-join-dependency/649355 "2022-09-15T12:22:48Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![anonymous\_user\_da30ee07](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_da30ee07](https://forums.unrealengine.com/u/anonymous_user_da30ee07)\
**Post date:** [September 15, 2022, 12:22pm UTC](https://forums.unrealengine.com/t/trivial-join-dependency/649355/1 "2022-09-15T12:22:48Z")

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I’m struggling to comprehend how to “operate” with join dependencies, so I have a query that I hope will help me make sense of it all.

[Wikipedia’s](https://en.wikipedia.org/wiki/Join_dependency) basic definition is as follows:

A table T is subject to a [join dependency](https://www.scaler.com/topics/join-dependency-in-dbms/) if T can always be recreated by joining multiple tables each having a subset of the attributes of T.

The definition of a trivial join dependence is as follows:

If one of the tables in the join has all the attributes of table T, the join dependency is called trivial.

Is it feasible that every join dependence of a relation R might be a simple join dependency if we collapse it into a lossless decomposition? Awesome would be one illustration.