（64）View the Exhibit and examine the data in the PROMO_CATEGORY and PROMO_COST columns of the PROMOTIONS table.

Evaluate the following two queries:

SELECT DISTINCT promo_category, to_char(promo_cost) "code"

FROM promotions ORDER BY code;

SELECT DISTINCT promo_category, promo_cost "code"

FROM promotions ORDER BY 1;

Which statement is true regarding the execution of the above queries?

A. Only the first query executes successfully.

B. Only the second query executes successfully.

C. Both queries execute successfully but give different results.

D. Both queries execute successfully and give the same result.

答案：（B）

解析：

--A(X), 列的别名加了引号，order by中别名也必须加引号

scott@TESTDB11>select sal, ename as "name" from emp order by name;

select sal, ename as "name" from emp order by name

*

ERROR at line 1:

ORA-00904: "NAME": invalid identifier

scott@TESTDB11>select sal, ename as "name" from emp order by "name";

SAL name

---------- ----------

1100 ADAMS

1600 ALLEN

2850 BLAKE

2450 CLARK

3000 FORD

950 JAMES

2975 JONES

5000 KING

1250 MARTIN

1300 MILLER

3000 SCOTT

800 SMITH

1500 TURNER

1250 WARD

14 rows selected.

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OCP 1Z0-051-64