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047-034

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-17 09:02:48 0 删除 编辑
34. View the Exhibit and examine the structure of the ORDERS and ORDER_ITEMS
tables. Evaluate the following SQL statement:
SELECT oi.order_id, product_id, order_date
FROM order_items oi JOIN orders o USING(order_id).
Which statement is true regarding the execution of this SQL statement?
A. The statement would not execute because table aliases are not allowed in
the JOIN clause.
B. The statement would not execute because the table alias prefix is not used
in the USING clause.
C. The statement would not execute because all the columns in the SELECT
clause are not prefixed with table aliases.
D. The statement would not execute because the column part of the USING clause
cannot have a qualifier in the SELECT list.
Answer: D
Qualifier:限定 clause:子句
Eg:SQL> select m.emp_no,m.ename "Man",e.ename "Emp"
2 from emp m join emp e
3 using (emp_no);
第 1 行出现错误:
ORA-25154: USING 子句的列部分不能有限定词

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