SELECT ActionID, FeedbackID, StaffID, ActionDate, ActionDetails,
       (SELECT StaffName, Department
        FROM staff
        WHERE staff.StaffID=action.StaffID)
FROM action;

SELECT a.ActionID, a.FeedbackID, a.StaffID, a.ActionDate, a.ActionDetails
, b.staffName, b.department

FROM action a
LEFT JOIN staff b on a.staffid=b.staffid

SELECT
    A.ActionID, A.FeedbackID, A.StaffID, A.ActionDate, A.ActionDetails,
    S.StaffName, S.Department

FROM Action AS A
    INNER JOIN Staff AS S ON Action.ActionID = Staff.ActionID