1Z0-051 QUESTION 16 Q操作符的使用

QUESTION 16
Evaluate the following query:
SQL> SELECT promo_name q'{'s start date was }' promo_begin_date
AS "Promotion Launches"
FROM promotions;
What would be the outcome of the above query?
A. It produces an error because flower braces have been used.
B. It produces an error because the data types are not matching.
C. It executes successfully and introduces an 's at the end of each promo_name in the output.

D. It executes successfully and displays the literal " {'s start date was } " for each row in the output.

答案：C

解析：

  题干有点错误，SELECT promo_name q'{'s start date was }' promo_begin_date AS "Promotion Launches" FROM promotions;执行会报错，因为promo_name后面和promo_begin_date前面都要加上连接符，正确的语句为SELECT promo_name||q'{'s start date was }' ||promo_begin_date AS "Promotion Launches" FROM promotions;，结果如下：

SQL> SELECT promo_name q'{'s start date was }' promo_begin_date
  2  AS "Promotion Launches"
  3  FROM promotions;
SELECT promo_name q'{'s start date was }' promo_begin_date
                  *
ERROR at line 1:
ORA-00923: FROM keyword not found where expected



SQL> SELECT promo_name||q'{'s start date was }'||promo_begin_date
  2  AS "Promotion Launches"
  3  FROM promotions;

Promotion Launches
--------------------------------------------------------------------------------

promotion1's start date was 12-OCT-13