1Z0-051-14题

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; 
Answer: C
1.DISTINCT只能出现在SQL的开头。
2.每个SQL语句只能有一个DISTINCT关键字。