When do all the researcher role staff start to work, and when do they stop working?
CREATE TABLE Project_Staff (
    date_from VARCHAR,
    date_to VARCHAR,
    role_code VARCHAR
)
SELECT date_from, date_to FROM Project_Staff WHERE role_code = 'researcher'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: When do all the researcher role staff start to work, and when do they stop working? ### Input: CREATE TABLE Project_Staff (
    date_from VARCHAR,
    date_to VARCHAR,
    role_code VARCHAR
) ### Response: SELECT date_from, date_to FROM Project_Staff WHERE role_code = 'researcher'