CREATE TABLE EMPLOYEE (EMP_NUM NUMBER, EMP_LNAME VARCHAR2, EMP_FNAME VARCHAR2, EMP_INITIAL VARCHAR2, EMP_JOBCODE VARCHAR2, EMP_HIREDATE DATETIME, EMP_DOB DATETIME)
CREATE TABLE PROFESSOR (EMP_NUM NUMBER, DEPT_CODE VARCHAR2, PROF_OFFICE VARCHAR2, PROF_EXTENSION VARCHAR2, PROF_HIGH_DEGREE VARCHAR2)
CREATE TABLE CLASS (CLASS_CODE VARCHAR2, CRS_CODE VARCHAR2, CLASS_SECTION VARCHAR2, CLASS_TIME VARCHAR2, CLASS_ROOM VARCHAR2, PROF_NUM NUMBER)
CREATE TABLE STUDENT (STU_NUM NUMBER, STU_LNAME VARCHAR2, STU_FNAME VARCHAR2, STU_INIT VARCHAR2, STU_DOB DATETIME, STU_HRS NUMBER, STU_CLASS VARCHAR2, STU_GPA FLOAT, STU_TRANSFER NUMBER, DEPT_CODE VARCHAR2, STU_PHONE VARCHAR2, PROF_NUM NUMBER)
CREATE TABLE ENROLL (CLASS_CODE VARCHAR2, STU_NUM NUMBER, ENROLL_GRADE VARCHAR2)
CREATE TABLE COURSE (CRS_CODE VARCHAR2, DEPT_CODE VARCHAR2, CRS_DESCRIPTION VARCHAR2, CRS_CREDIT FLOAT)
CREATE TABLE DEPARTMENT (DEPT_CODE VARCHAR2, DEPT_NAME VARCHAR2, SCHOOL_CODE VARCHAR2, EMP_NUM NUMBER, DEPT_ADDRESS VARCHAR2, DEPT_EXTENSION VARCHAR2)

How many students taking a course who received an A or C? Group by students' last name with a bar chart, and display by the STU_LNAME in desc.
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 STU_LNAME DESC
SELECT "STU_LNAME", COUNT("STU_LNAME") FROM "STUDENT" "T1" JOIN "ENROLL" "T2" ON "T1"."STU_NUM" = "T2"."STU_NUM" AND ("T2"."ENROLL_GRADE" = 'A' OR "T2"."ENROLL_GRADE" = 'C') GROUP BY "STU_LNAME" ORDER BY "STU_LNAME" DESC