OCP-1Z0-051-V9.02-14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.  --each income  level中没有重复的credit amounts
Which  query would give the required result?
A.

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

 

sh@TESTDB> SELECT  cust_income_level, DISTINCT cust_credit_limit * 0.50      2  AS "50% Credit Limit"   3  FROM customers; SELECT  cust_income_level, DISTINCT cust_credit_limit * 0.50                           *ERROR at line 1:ORA-00936: missing expression

语法错误，DISTINCT不应该放在第二列，应该放在第一列中

sh@TESTDB> SELECT DISTINCT  cust_income_level,cust_credit_limit * 0.50  2  AS "50% Credit Limit"  3  FROM customers where rownum<6;CUST_INCOME_LEVEL              50% Credit Limit------------------------------ ----------------G: 130,000 - 149,999                       5500G: 130,000 - 149,999                       4500G: 130,000 - 149,999                       3500G: 130,000 - 149,999                        750

B.

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

 

同A，语法错误，DISTINCT不应该放在第二个

SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50      2  AS "50% Credit Limit"   3  FROM customers; SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50                                   *ERROR at line 1:ORA-00936: missing expression

 

C.

SELECT DISTINCT cust_income_level   '   '  cust_credit_limit * 0.50 
AS "50% Credit Limit"
FROM customers;

sh@TESTDB> SELECT DISTINCT cust_income_level   '   '  cust_credit_limit * 0.50   2  AS "50% Credit Limit"   3  FROM customers; SELECT DISTINCT cust_income_level   '   '  cust_credit_limit * 0.50                                    *ERROR at line 1:ORA-00923: FROM keyword not found where expected

这道题愿意为用' '连接两个列，可能用错，应为||来连接，不过DISTINCT的位置 对的

sh@TESTDB> SELECT DISTINCT cust_income_level || cust_credit_limit * 0.50  2  AS "50% Credit Limit"   3  FROM customers where rownum<6;50% Credit Limit----------------------------------------------------------------------G: 130,000 - 149,999750G: 130,000 - 149,9994500G: 130,000 - 149,9993500G: 130,000 - 149,9995500

 

D.

SELECT cust_income_level ' ' cust_credit_limit * 0.50 AS "50% Credit Limit"
FROM customers

D没有满足NOT show any repeated的条件。

 

此题答案C