多项选择题
A. listing the employees who earn the same amount of commission as employee 3
B. finding the total commission earned by the employees in department 10
C. finding the number of employees who earn a commission that is higher than the average commission of the company
D. listing the departments whose average commission is more that 600
E. listing the employees who do not earn commission and who are working for department 20 in descending order of the employee ID
F. listing the employees whose annual commission is more than 6000
单项选择题 User Mary has a view called EMP_DEPT_LOC_VU that was created based on the EMPLOYEES, DEPARTMENTS, and LOCATIONS tables. She has the privilege to create a public synonym, and would like to create a synonym for this view that can be used by all users of the database.Which SQL statement can Mary use to accomplish that task?（）
多项选择题 Which two statements about subqueries are true? （）
单项选择题 Which substitution variable would you use if you want to reuse the variable without prompting the user each time?（）
