多项选择题
A. DELETE employees;
B. DESCRIBE employees;
C. ROLLBACK TO SAVEPOINT C;
D. GRANT SELECT ON employees TO SCOTT;
E. ALTER TABLE employees SET UNUSED COLUMN sal;
F. Select MAX(sal) FROM employees WHERE department_id = 20;
单项选择题 What is true about sequences?（）
单项选择题 The DBA issues this SQL command: What privileges does the user Scott have at this point?（）
单项选择题 Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2 (25) LAST_NAME VARCHAR2 (25) HIRE_DATE DATE Which UPDATE statement is valid?（）