151.View the Exhibit and examine the structure of the CUSTOMERS and CUST_HISTORY tables.

151.View the Exhibit and examine the structure of the CUSTOMERS and CUST_HISTORY tables.
The CUSTOMERS table contains the current location of all currently active customers. The
CUST_HISTORY table stores historical details relating to any changes in the location of all current as well
as previous customers who are no longer active with the company.
You need to find those customers who have never changed their address.
Which SET operator would you use to get the required output?


A.MINUS
B.UNION
C.INTERSECT
D.UNION ALL
答案：A
解析：
MINUS：取差
UNION：取加，但是排除重复
INTERSECT：取交集
UNION ALL：取加，不排除重复
从题目中可以看出选A