多项选择题 Which three SELECT statements displays 2000 in the format "$2,000.00"? （）

多项选择题 For which two constraints does the Oracle Server implicitly create a unique index? （）

单项选择题 You created a view called EMP_DEPT_VU that contains three columns from the EMPLOYEES and DEPARTMENTS tables: EMPLOYEE_ID, EMPLOYEE_NAME AND DEPARTMENT_NAME. The DEPARTMENT_ID column of the EMPLOYEES table is the foreign key to the primary key DEPARTMENT_ID column of the DEPARTMENTS table. You want to modify the view by adding a fourth column, MANAGER_ID of NUMBER data type from the EMPLOYEES tables. How can you accomplish this task?（）