How can you specify a dependency between dbt models?

The correct approach to specify a dependency between dbt models is by using the ref function in SQL. This function allows you to explicitly define relationships between models, ensuring that dbt understands the order of execution when building your data pipeline. When you call another model within a model's SQL file using the ref function, dbt is made aware that the first model (the one being referenced) must be built before the second model (the one making the reference). This capability allows for dependency management and ensures that all relevant data transformations occur in the correct sequence, which is essential for maintaining the integrity and accuracy of the final dataset.

While other options might be relevant in different contexts, they do not serve the explicit purpose of establishing model dependencies within the dbt framework. For instance, commands in the CLI can execute dbt models but do not inherently create a dependency. Model configurations in a .yml file are used primarily for defining metadata, tests, and documentation but do not set up dependencies between models. Unique constraints in a database relate to data integrity but do not influence the order of model execution or dependency resolution within dbt's workflow.