The view updates represents an incremental batch of newly ingested data to be inserted or updated in the customers table.

The following logic is used to process these records:

MERGE INTO customers
USING (
  SELECT updates.customer_id AS merge_key, updates.*
  FROM updates
  UNION ALL
  SELECT NULL AS merge_key, updates.*
  FROM updates JOIN customers
  ON updates.customer_id = customers.customer_id
  WHERE customers.current = true AND updates.address <> customers.address
) staged_updates
ON customers.customer_id = staged_updates.merge_key
WHEN MATCHED AND customers.current = true AND customers.address <> staged_updates.address THEN
  UPDATE SET current = false, end_date = staged_updates.effective_date
WHEN NOT MATCHED THEN
  INSERT (customer_id, address, current, effective_date, end_date)
  VALUES (staged_updates.customer_id, staged_updates.address, true, staged_updates.effective_date, null)

MERGE INTO customers
USING (
  SELECT updates.customer_id AS merge_key, updates.*
  FROM updates
  UNION ALL
  SELECT NULL AS merge_key, updates.*
  FROM updates JOIN customers
  ON updates.customer_id = customers.customer_id
  WHERE customers.current = true AND updates.address <> customers.address
) staged_updates
ON customers.customer_id = staged_updates.merge_key
WHEN MATCHED AND customers.current = true AND customers.address <> staged_updates.address THEN
  UPDATE SET current = false, end_date = staged_updates.effective_date
WHEN NOT MATCHED THEN
  INSERT (customer_id, address, current, effective_date, end_date)
  VALUES (staged_updates.customer_id, staged_updates.address, true, staged_updates.effective_date, null)

Which statement describes this implementation?_