# How to create an automatic relation based on a number of different criteria

**URL:** <https://community.fibery.io/t/how-to-create-an-automatic-relation-based-on-a-number-of-different-criteria/4140>\
**Category:** Get Help\
**Created:** [March 16, 2023, 10:51pm UTC](https://community.fibery.io/t/how-to-create-an-automatic-relation-based-on-a-number-of-different-criteria/4140 "2023-03-16T22:51:37Z")\
**Posts on this page:** 1\
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**Author:** ![Chr1sG](https://sea2.discourse-cdn.com/flex020/user_avatar/community.fibery.io/chr1sg/32/3941_2.png) [@Chr1sG](https://community.fibery.io/u/Chr1sG)\
**Post date:** [March 17, 2023, 7:11am UTC](https://community.fibery.io/t/how-to-create-an-automatic-relation-based-on-a-number-of-different-criteria/4140/3 "2023-03-17T07:11:59Z")

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> [@tpaktop](#):
>
> Having `union` function would be way nicer though /cc @Chr1sG

The union function is in the backlog, but I’m not sure when it might get implemented I’m afraid.

> [@How to union two list fields in the same Database?](https://community.fibery.io/t/how-to-union-two-list-fields-in-the-same-database/2467):
>
> I have two list fields in my Database: Tags and [Project Tags]. (Tags is an x:many relation and [Project Tags] is a lookup of an x:many field.) I want to combine them into a single list field [All Tags], so if (eg) Tags = (foo, bar) and [Project Tags] = (baz, bam) then [All Tags] = (foo, bar, baz, bam). Is this possible? I can’t figure out how to do it with a formula or a lookup. Extra complication: ultimately I actually want the unique set of all tags, so if (eg) Tags = (foo, bar) and [Pro…

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