OCP认证051考试题库：11g-v9.02-第137题
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137. View the Exhibits and examine PRODUCTS and SALES tables.
You issue the following query to display product name and the number of times the product has been
sold:
SQL>SELECT p.prod_name, i.item_cnt
FROM (SELECT prod_id, COUNT(*) item_cnt
FROM sales
GROUP BY prod_id) i RIGHT OUTER JOIN products p
ON i.prod_id = p.prod_id;
What happens when the above statement is executed?
A. The statement executes successfully and produces the required output.
B. The statement produces an error because ITEM_CNT cannot be displayed in the outer query.
C. The statement produces an error because a subquery in the FROM clause and outer-joins cannot be
used together.
D. The statement produces an error because the GROUP BY clause cannot be used in a subquery in the
FROM clause.
Answer: A
试题解析：
通过子查询，查询出产品卖出去的次数。
在通过右连接产品表，显示出所有产品。
