选择first_name按升序的奇数行，但是输出时不排序
对于employees表中，给出奇数行的first_name
http://www.nowcoder.com/practice/e3cf1171f6cc426bac85fd4ffa786594
T2.FIRST_NAME
FROM
EMPLOYEES T2,
(
SELECT
T1.FIRST_NAME,
ROW_NUMBER() OVER(ORDER BY FIRST_NAME) AS RO
FROM
EMPLOYEES T1
)T3
WHERE T2.FIRST_NAME = T3.FIRST_NAME
AND T3.RO % 2 = 1
