H18 Define a relational model

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H18 Define a relational model

Goal: Describe tables and their relationships together.

Prerequisites: H17; dm is a core dependency.

A dm model retains multiple tables. It does not automatically flatten them into one output table.

training_step(
  "H18",
  {
    portfolio_model <- dm::dm(
      policies = linked_policies,
      customers = customers,
      brokers = brokers
    ) |>
      dm::dm_add_pk(policies, policy_id) |>
      dm::dm_add_pk(customers, customer_id) |>
      dm::dm_add_pk(brokers, broker_id) |>
      dm::dm_add_fk(policies, customer_id, customers) |>
      dm::dm_add_fk(policies, broker_id, brokers)
    print(portfolio_model)
  },
  needs = c("H17")
)

Expected result: Three tables and two foreign-key relationships.

Task: Which table holds the region?