本文深入探讨SQL复合查询的概念，通过具体实例解释了INTERSECT、MINUS操作符的应用，以及如何理解并实现产品销售与成本记录之间的关联查询。
154.View the Exhibit and evaluate structures of the SALES, PRODUCTS, and COSTS tables.
Evaluate the following SQL statement:
SQL>SELECT prod_id FROM products
INTERSECT
SELECT prod_id FROM sales
MINUS
SELECT prod_id FROM costs;
Which statement is true regarding the above compound query?
A.It produces an error.
B.It shows products that were sold and have a cost recorded.
C.It shows products that were sold but have no cost recorded.
D.It shows products that have a cost recorded irrespective of sales.
答案：C
解析：参考前几道题的说明选择C
Evaluate the following SQL statement:
SQL>SELECT prod_id FROM products
INTERSECT
SELECT prod_id FROM sales
MINUS
SELECT prod_id FROM costs;
Which statement is true regarding the above compound query?
A.It produces an error.
B.It shows products that were sold and have a cost recorded.
C.It shows products that were sold but have no cost recorded.
D.It shows products that have a cost recorded irrespective of sales.
答案：C
解析：参考前几道题的说明选择C
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