FK relationship to table already in the database about dbt_constraints

[sfc-gh-dflippo]

Any table not in your project should be referenced as a source. The dbt Constraints package optionally allows you to create FK, UK, and PK constraints on sources. As described in the readme, you enable this extra feature by adding this to your dbt_project.yml

vars:
  dbt_constraints_sources_enabled: true

It is important to remember that you must have a PK or UK on the parent table. If you have sufficient permissions, you could define those PK/UK on sources in dbt. If you don't you would need to add such constraints outside of dbt before you could create a FK to those tables. Either way, the package will verify whether there is a PK/UK in place before creating a FK.

I have examples using this feature in the integration tests. I recommend reviewing these two YAML that have constraints on sources, between sources, and between models and sources:
https://github.com/Snowflake-Labs/dbt_constraints/blob/main/integration_tests/models/sources.yml
https://github.com/Snowflake-Labs/dbt_constraints/blob/main/integration_tests/models/schema.yml