单项选择题
A.SELECT last_name, department_name FROM employees NATURAL JOIN departments;
B.SELECT last_name, department_name FROM employees JOIN departments ;
C.SELECT last_name, department_name FROM employees e JOIN departments d ON (e.department_id = d.department_id);
D.SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);
E.SELECT last_name, department_name FROM employees FULL JOIN departments ON (e.department_id = d.department_id);
F.SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id);
单项选择题 Which view should a user query to display the columns associated with the constraints on a table owned by the user?（）
单项选择题 Examine the description of the EMPLOYEES table: EMP_ID NUMBER(4) NOT NULL LAST_NAME VARCHAR2(30) NOT NULL FIRST_NAME VARCHAR2(30) DEPT_ID NUMBER(2) Which statement produces the number of different departments that have employees with last name Smith?（）
多项选择题 Which three statements about subqueries are true? （）
