From SQL*Plus, you issue this SELECT statement:
SELECT*
FROM order;
You use this statement to retrieve data from a data table for （）.

单项选择题Evaluate this SQL statement: SELECT e.employee_id, (.15* e.salary) + (.5 * e.commission_pct) + (s.sales amount * (.35 * e.bonus)) AS CALC_VALUE FROM employees e, sales s WHERE e.employee_id = s.emp_id; What will happen if you remove all the parentheses from the calculation? （）

A. The value displayed in the CALC_VALUE column will be lower.
B. The value displayed in the CALC_VALUE column will be higher.
C. There will be no difference in the value displayed in the CALC_VALUE column.
D. An error will be reported.

单项选择题The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20) Which statement finds the rows in the CUSTOMERS table that do not have a postal code? （）

A. SELECT customer_id, customer_name FROM customers WHERE postal_code CONTAINS NULL;
B. SELECT customer_id, customer_name FROM customers WHER postal_code = ' ___________';
C. SELECT customer_id, customer_name FROM customers WHERE postal _ code IS NULL;
D. SELECT customer_id, customer_name FROM customers WHERE postal code IS NVL;
E. SELECT customer_id, customer_name FROM customers WHERE postal_code = NULL;

单项选择题You would like to display the system date in the format Monday, 01 June, 2001 . Which SELECT statement should you use? （）

A. SELECT TO_DATE(SYSDATE, 'FMDAY, DD Month, YYYY') FROM dual;
B. SELECT TO_CHAR(SYSDATE, 'FMDD, DY Month, 'YYYY') FROM dual;
C. SELECT TO_CHAR(SYSDATE, 'FMDay, DD Month, YYYY') FROM dual;
D. SELECT TO_CHAR(SYSDATE, 'FMDY, DDD Month, YYYY') FROM dual;
E. SELECT TO_DATE(SYSDATE, 'FMDY, DDD Month, YYYY') FROM dual;

单项选择题Evaluate these two SQL statements: SELECT last_name, salary , hire_date FROM EMPLOYEES ORDER BY salary DESC; SELECT last_name, salary, hire_date FROM EMPLOYEES ORDER BY 2 DESC; What is true about them? （）

A. The two statements produce identical results.
B. The second statement returns a syntax error.
C. There is no need to specify DESC because the results are sorted in descending order by default.
D. The two statements can be made to produce identical results by adding a column alias for the salary column in the second SQL statement.

单项选择题The EMP table has these columns: ENAME VARCHAR2(35) SALARY NUMBER(8,2) HIRE_DATE DATE Management wants a list of names of employees who have been with the company for more than five years. Which SQL statement displays the required results? （）

A. SELECT ENAME FROM EMP WHERE SYSDATE-HIRE_DATE >5;
B. SELECT ENAME FROM EMP WHERE HIRE_DATE-SYSDATE >5;
C. SELECT ENAME FROM EMP WHERE (SYSDATE_HIRE_DATE)/365 >5;
D. SELECT ENAME FROM EMP WHERE (SYSDATE_HIRE_DATE)*/365 >5;