Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_42 (commercial_operation VARCHAR, unit VARCHAR)
### Question:
When was the Hamaoka-4 unit commercial operation date?
### Answer:
SELECT commercial_operation FROM table_name_42 WHERE unit = "hamaoka-4"