1z0-071 Oracle Database 12c SQL 第10题 alias name别名

Q10. Examine the structure of the MEMBERS table:
Name Null? Type
-—————– ————— ——————————
MEMBER_ID NOT NULL VARCHAR2 (6)
FIRST_NAME VARCHAR2 (50)
LAST_NAME NOT NULL VARCHAR2 (50)
ADDRESS VARCHAR2 (50)
You execute the SQL statement:
SQL > SELECT member_id, ‘ ‘ , first_name, ‘ ‘ , last_name "ID FIRSTNAME LASTNAME " FROM members;
What is the outcome?
A. It fails because the alias name specified after the column names is invalid.
B. It fails because the space specified in single quotation marks after the first two column names is invalid.
C. It executes successfully and displays the column details in a single column with only the alias column heading.

D. It executes successfully and displays the column details in three separate columns and replaces only the last column heading with the alias.

Correct Answer: D

A.它失败了，因为在列名后面指定的别名是无效的。

B.它失败了，因为前两个列名后的单引号中指定的空间无效。

C.它成功执行，并在只有别名列标题的单列中显示列详细信息。

D.它成功执行并在三个单独的列中显示列详细信息，并仅替换带有别名的最后一个列标题。