单项选择题 Which SQL statement would you use to remove a view called EMP_DEPT_VU from your schema?（）

多项选择题 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?（）

多项选择题 Which four are valid Oracle constraint types? （）