instruction: How many students taking a course who received an A or C? Group by students' last name with a bar chart, display in ascending by the the number of stu lname.
response: SELECT STU_LNAME, COUNT(STU_LNAME) FROM STUDENT AS T1 JOIN ENROLL AS T2 ON T1.STU_NUM = T2.STU_NUM WHERE T2.ENROLL_GRADE = 'C' OR T2.ENROLL_GRADE = 'A' GROUP BY STU_LNAME ORDER BY COUNT(STU_LNAME)