每日一练001

如下是BOOKS_TRANSACTIONS表的结构：
DESC BOOKS_TRANSACTIONS
TRANSACTION_ID NOT NULL VARCHAR2
BORROWED_DATE DATE
DUE_DATE DATE
BOOK_ID VARCHAR2
MEMBER_ID VARCHAR2 (6)
需求：打印输出BOOKS_TRANSACTIONS表的MEMBER_ID,DUE_DATE的信息以字符’$2’作为LATE_FEE信息。如下哪个SQL是正确的？
A) SELECT member_id AS MEMBER_ID, due_date AS DUE_DATE, $2 AS LATE_FEE FROM BOOKS_TRANSACTIONS;
B) SELECT member_id AS “MEMBER_ID”, due_date AS “DUE_DATE”, ‘$2’ AS " LATE_FEE” FROM BOOKS_TRANSACTIONS;
C) SELECT member_id AS “MEMBER_ID”, due_date AS “DUE_DATE”, $2 AS “LATE_FEE” FROM BOOKS_TRANSACTIONS;
答案：B
本题考点：别名和字符输出
别名加 “” 大小写敏感，默认为大写
$2作为字符输出需要加’’,否则不识别