【OCP 12c】最新CUUG OCP-071考试题库（64题）

64、(22-7) choose the best answer:

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 the table alias prefix is not used in the USING clause.

B) The statement would not execute because the column part of the USING clause cannot have a qualifier in the SELECT list.

C) The statement would not execute because table aliases are not allowed in the JOIN clause.

D) The statement would not execute because all the columns in the SELECT clause are not prefixed with table aliases.

Anser：B

(解析：该题考的是语法，因为 USING 子句的列部分在 SELECT 列表中不能具有限定符，所以该语句不会执行，把前缀 oi 去掉就可以了，但是其它的列可以用表的别名做为前缀：

SELECT order_id,oi.product_id,order_date

FROM order_items oi JOIN orders o

USING(order_id);

?

)该题之前有过类似的考题。