One to one relationship in two tables

Hello everyone and thanks for the help.

I have a Customers table linked to a Services table. And the behavior we need is that only one service can be linked to one customer. That is, if Customer A is linked to Service A, Customer B should not be able to be linked to Service A (because it was previously linked to Customer A).

I have tried using a formula in the filter of the linked column, but no formula I place works. Which one could work?

Greetings,

Hi @Mario_Yaranga,

can you please share your doc or create a demo doc and share this?
Here is a guide: https://coda.io/@jannis/coda-community/how-to-share-a-doc-with-the-coda-community-16

Jannis