问题：

[多选]

Examine the data from the EMP table:

The COMMISSION column shows the monthly commission earned by the employee.Which three tasks would require subqueries or joins in order to perform in a single step?（）

A . Deleting the records of employees who do not earn commission.
B . Increasing the commission of employee 3 by the average commission earned in department 20.
C . Finding the number of employees who do NOT earn commission and are working for department 20.
D . Inserting into the table a new employee 10 who works for department 20 and earns a commission that is equal to the commission earned by employee 3.
E . Creating a table called COMMISSION that has the same structure and data as the columns EMP_ID and COMMISSIONS of the EMP table.
F . Decreasing the commission by 150 for the employees who are working in department 30 and earning a commission of more then 800.