The data operations team wants a customer membership report across the BI and Finance systems.
Using bi_customers and fin_customers, include every customer ID found in either system, with one row per distinct ID.
For each customer, report two Boolean flags:
01in_bi: TRUE if the customer appears in BI; otherwise FALSE.
02in_finance: TRUE if the customer appears in Finance; otherwise FALSE.
The flags should show the customer's actual presence in the two source lists.
Ordering: Sort by customer_id in ascending order.