1Z0-051 QUESTION 14 DISTINCT的用法
2014-05-09 23:32
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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选项报错
SQL> SELECT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Credit
Limit"
2 FROM customers;
SELECT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Credit Limit
"
*
ERROR at line 1:
ORA-00936: missing expression
--B选项报错
SQL> SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50
% Credit Limit"
2 FROM customers;
SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Cre
dit Limit"
*
ERROR at line 1:
ORA-00936: missing expression
--C选项得出正确的结果
SQL> SELECT DISTINCT cust_income_level ||' '|| cust_credit_limit * 0.50 AS "50%
Credit Limit"
2 FROM customers;
50% Credit Limit
--------------------------------------------------------------------------------
level4 2500
level12 25000
level2 25000
level3 250000
level1 2500
--D选项把重复的结果都显示出来了
SQL> SELECT cust_income_level|| ' ' ||cust_credit_limit * 0.50 AS "50% Credit Li
mit"
2 FROM customers;
50% Credit Limit
--------------------------------------------------------------------------------
level1 2500
level2 25000
level3 250000
level12 25000
level1 2500
level4 2500
6 rows selected.
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选项报错
SQL> SELECT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Credit
Limit"
2 FROM customers;
SELECT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Credit Limit
"
*
ERROR at line 1:
ORA-00936: missing expression
--B选项报错
SQL> SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50
% Credit Limit"
2 FROM customers;
SELECT DISTINCT cust_income_level, DISTINCT cust_credit_limit * 0.50 AS "50% Cre
dit Limit"
*
ERROR at line 1:
ORA-00936: missing expression
--C选项得出正确的结果
SQL> SELECT DISTINCT cust_income_level ||' '|| cust_credit_limit * 0.50 AS "50%
Credit Limit"
2 FROM customers;
50% Credit Limit
--------------------------------------------------------------------------------
level4 2500
level12 25000
level2 25000
level3 250000
level1 2500
--D选项把重复的结果都显示出来了
SQL> SELECT cust_income_level|| ' ' ||cust_credit_limit * 0.50 AS "50% Credit Li
mit"
2 FROM customers;
50% Credit Limit
--------------------------------------------------------------------------------
level1 2500
level2 25000
level3 250000
level12 25000
level1 2500
level4 2500
6 rows selected.
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