Take a look at these 2 questions

Question

271. Which two statements are true regarding the types of table joins available in Oracle Database 10g?
(Choose two.)
A. You can use the JOIN clause to join only two tables.
B. You can explicitly provide the join condition with a NATURAL JOIN.
C. You can use the USING clause to join tables on more than one column.
D. You can use the ON clause to specify multiple conditions while joining tables.
Answer: CD
----i don`t think C is the the right answer,can you give a sample
272. Which two statements are true regarding subqueries? (Choose two.)
A. The ORDER BY clause can be used in the subquery.
B. A subquery can be used in the FROM clause of a SELECT statement.
C. If the subquery returns NULL, the main query may still return result rows.
D. A subquery can be placed in a WHERE clause, GROUP BY clause, or a HAVING clause.
E. Logical operators, such as AND, OR and NOT, cannot be used in the WHERE clause of a subquery.
Answer: AB
to Option A,i test it using the given sql below
select invcode
from ord_item
where item_id in (select item_id from ord_item where ord_id = 1 order by item_id);
it cannot work at least under this situation ...it means that The ORDER BY clause can be used in the subquery may be wrong.
what about your oponion?
Edited by: hibob on Jul 25, 2012 3:12 PM

Answer 1

Hai
Please go through the followings. You can understand that...
1. The keyword USING is similar to the natural join, in the sense that its use depends
on the presence of identically named columns in the JOIN. However, USING can
be used with both inner and outer joins. For example:
SELECT EMPLOYEE_ID, LAST_NAME, STREET_ADDRESS
FROM EMPLOYEES LEFT JOIN ADDRESSES
USING (EMPLOYEE_ID);
2. SELECT * FROM
(SELECT EMPNO,ENAME,DEPTNO FROM EMP ORDER BY EMPNO)
A,
(SELECT DEPTNO,DNAME FROM DEPT ORDER BY DEPTNO) D
WHERE A.DEPTNO=D.DEPTNO