（14）Using the CUSTOMERS table, you need to generate a report that shows 50% of each credit amount in each income level.

The report should NOT show any repeated credit amounts in each income level. Which query would give the required result?

A.SELECT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Credit Limit" FROM customers;

B. SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Credit Limit" FROM customers;

C.SELECT DISTINCT cust_income_level || cust_credit_limit * 0.50 AS "50% Credit Limit" FROM customers;

D. SELECT cust_income_level || cust_credit_limit * 0.50 AS "50% Credit Limit" FROM customers;

答案：（C）

解析：

A. DISTINCT关键字只能出现在第一列之前。

B. 一个SELECT语句上只能出现一个DISTINCT关键字

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Oracle Certificate Profession 1Z0-051-14