Table schema:
CREATE TABLE professor (prof_office VARCHAR, emp_num VARCHAR); CREATE TABLE course (crs_description VARCHAR, crs_code VARCHAR); CREATE TABLE CLASS (prof_num VARCHAR, crs_code VARCHAR); CREATE TABLE employee (emp_fname VARCHAR, emp_num VARCHAR)

Question: Find the first names and offices of all instructors who have taught some course and also find the course description.
SQL: SELECT T2.emp_fname, T4.prof_office, T3.crs_description FROM CLASS AS T1 JOIN employee AS T2 ON T1.prof_num = T2.emp_num JOIN course AS T3 ON T1.crs_code = T3.crs_code JOIN professor AS T4 ON T2.emp_num = T4.emp_num