出自:Oracle认证
The STUDENT_GRADES table has these columns: 
The register has requested a report listing the students' grade point averages (GPA), sorted from highest grade point average to lowest within each semester, starting from the earliest date. Which statement accomplishes this?（）
A:SELECT student_id, semester_end, gpa FROM student_grades ORDER BY semester_end DESC, gpa DESC;
B:SELECT student_id, semester_end, gpa FROM student_grades ORDER BY semester_end ASC, gpa ASC;
C:SELECT student_id, semester_end, gpa FROM student_grades ORDER BY semester_end, gpa DESC;
D:SELECT student_id, semester_end, gpa FROM student_grades ORDER BY gpa DESC, semester_end DESC;
E:SELECT student_id, semester_end, gpa FROM student_grades ORDER BY gpa DESC, semester_end ASC;
Examine the structure of the EMPLOYEES and DEPARTMENTS tables: EMPLOYEES EMPLOYEE_ID NUMBER DEPARTMENT_ID NUMBER MANAGER_ID NUMBER LAST_NAME VARCHAR2(25) DEPARTMENTS DEPARTMENT_ID NUMBER MANAGER_ID NUMBER DEPARTMENT_NAME VARCHAR2(35) LOCATION_ID NUMBER You want to create a report displaying employee last names, department names, and locations. Which query should you use to create an equi-join?（）
A:SELECT last_name, department_name, location_id FROM employees , department ;
B:SELECT employees.last_name, departments.department_name, departments.location_id FROM employees e, departments D WHERE e.department_id = d.department_id;
C:SELECT e.last_name, d.department_name, d.location_id FROM employees e, departments D WHERE manager_id = manager_id;
D:SELECT e.last_name, d.department_name, d.location_id FROM employees e, departments D WHERE e.department_id = d.department_id;
What is the result？（）
What is the result?（）
Which statement is true about the class of an object that can reference the variable base？（）