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 Projects (project_details VARCHAR, project_id VARCHAR, role_code VARCHAR); CREATE TABLE Project_Staff (project_details VARCHAR, project_id VARCHAR, role_code VARCHAR)
### Question:
List the project details of the projects which did not hire any staff for a researcher role.
### Answer:
SELECT project_details FROM Projects WHERE NOT project_id IN (SELECT project_id FROM Project_Staff WHERE role_code = 'researcher')