instruction: Show the number of courses for each instructor in a stacked bar chart The x-axis is instructor's first name and group by course description, and list by the y axis in descending please.
response: SELECT EMP_FNAME, COUNT(EMP_FNAME) 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 GROUP BY CRS_DESCRIPTION, EMP_FNAME ORDER BY COUNT(EMP_FNAME) DESC