CREATE TABLE CLASS (crs_code VARCHAR2, prof_num VARCHAR2)
CREATE TABLE employee (emp_fname VARCHAR2, emp_num VARCHAR2)

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
SELECT "T2"."emp_fname", "T1"."crs_code" FROM "CLASS" "T1" JOIN "employee" "T2" ON "T1"."prof_num" = "T2"."emp_num"