Which substitution variable would you use if you want to reuse the variable without prompting the user each time?（）

单项选择题Which constraint can be defines only at the column level?（）

A. UNIQUE
B. NOT NULL
C. CHECK
D. PRIMARY KEY
E. FOREIGN KEY

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 INSERT statement is valid?（）

A. INSERT INTO employees (employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01/01/01);
B. INSERT INTO employees(employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01 january 01');
C. INSERT INTO employees(employee_id, first_name, last_name, Hire_date) VALUES (1000, 'John', 'smith', To_ date ('01/01/01));
D. INSERT INTO employees(employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01-Jan-01');

单项选择题In which scenario would TOP N analysis be the best solution?（）

A. You want to identify the most senior employee in the company.
B. You want to find the manager supervising the largest number of employees.
C. You want to identify the person who makes the highest salary for all employees.
D. You want to rank the top three sales representatives who have sold the maximum number of products.

多项选择题Which three are true regarding the use of outer joins?（）

A. You cannot use IN operator in a condition that involves an outerjoin.
B. You use (+) on both sides of the WHERE condition to perform an outerjoin.
C. You use (*) on both sides of the WHERE condition to perform an outerjoin.
D. You use an outerjoin to see only the rows that do not meet the join condition.
E. In the WHERE condition, you use (+) following the name of the column in the table without matching rows, to perform an outerjoin.
F. You cannot link a condition that is involved in an outerjoin to another condition by using the OR operator.

单项选择题Exhibit Examine the data in the EMPLOYEES and DEPARTMENTS tables. You want to retrieve all employees last names, along with their managers last names and their department names. Which query would you use?（）

A. SELECT last_name, manager_id, department_name FROM employees e FULL OUTER JOIN department d ON (e.department_id = d.department_id);
B. SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.managaer_id = m.employee_id) LEFT OUTER JOIN department d ON (e.department_id = d.department_id);
C. SELECT e.last_name, m.last_name, department_name FROM employees e RIGT OUTER JOIN employees m on ( e.manager_id = m.employee_id) FULL OUTER JOIN department d ON (e.department_id = d.department_id);
D. SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGT OUTER JOIN department d ON (e.department_id = d.department_id);
E. SELECT e.last_name, m.last_name, department_name FROM employees e RIGHT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id)
F. SELECT last_name, manager_id, department_name FROM employees e JOIN department d ON (e.department_id = d.department_id);