OCP-1Z0-051-V9.02-8题

8. View the Exhibit and examine the structure of the CUSTOMERS table.

Which two tasks would require subqueries or joins to be executed in a single statement? (Choose two.) 

A. listing of customers who do not have a credit limit and were born before 1980

B. finding the number of customers, in each city, whose marital status is 'married'

C. finding the average credit limit of male customers residing in 'Tokyo' or 'Sydney'

D. listing of those customers whose credit limit is the same as the credit limit of customers residing in the

city 'Tokyo'

E. finding the number of customers, in each city, whose credit limit is more than the average credit limit of

all the customers

Answer: DE

答案解析：

参考：http://blog.csdn.net/rlhua/article/details/12879585

ABC不用子查询就可以查询出，题意选择两个，排除ABC,选择DE

A. 列出没有信贷限额并且1980年以前出生的客户。

SELECT 客户 from 表名 where 信贷限额 is null and 出生日期>1980;

B. 查找每个城市的已婚客户的数量。

SELECT 城市名，COUNT(*) FROM 表名 where 客户婚否=‘结婚’ group by 城市名;

C. 查找属于'Tokyo'或者 'Sydney'两个城市的男性客户的平均信贷限额。

SELECT 城市名， AVG(信贷限额) from 表名 where 性别=‘男’ and 城市 in（'Tokyo'， 'Sydney'） group by 城市名

D 列出与'Tokyo'城市的客户的信贷限额相等的客户

E. 查找每个城市的客户数量，这些客户的信贷限额大于所有客户的平均信贷限额。