Find the first names of all instructors who have taught some course and the course code.
SELECT T2.emp_fname ,  T1.crs_code FROM CLASS AS T1 JOIN employee AS T2 ON T1.prof_num  =  T2.emp_num
first names of all instructors = T2.emp_fname; have taught some course = JOIN condition on instructor and course; course code = T1.crs_code;