单项选择题 Evaluate the SQL statement: 1 SELECT a.emp_name, a.sal, a.dept_id, b.maxsal 2 FROM employees a, 3 (SELECT dept_id, MAX(sal) maxsal 4. FROM employees 5 GROUP BY dept_id) b 6 WHERE a.dept_id = b.dept_id 7 AND a. asl < b. maxsal; What is the result of the statement? （）

单项选择题 The EMPLOYEE tables has these columns: LAST_NAME VARCHAR2(35) SALARY NUMBER(8,2) COMMISSION_PCT NUMBER(5,2) You want to display the name and annual salary multiplied by the commission_pct for all employees. For records that have a NULL commission_pct, a zero must be displayed against the calculated column. Which SQL statement displays the desired results? （）

多项选择题 Examine the description of the STUDENTS table: STD_ID NUMBER(4) COURSE_ID VARCHARD2(10) START_DATE DATE END_DATE DATE Which two aggregate functions are valid on the START_DATE column?（）