自用题解
对于employees表中，给出奇数行的first_name
http://www.nowcoder.com/questionTerminal/e3cf1171f6cc426bac85fd4ffa786594
通过窗口函数生成一张新的表
select
`emp_no` as `e_n`,
`first_name`,
row_number() over(order by `first_name` asc) as `r_num`
from
`employees` 
然后与原表进行连接操作
select
`e`.`first_name`
from
`employees` as `e`
inner join
(
select
`emp_no` as `e_n`,
`first_name`,
row_number() over(order by `first_name` asc) as `r_num`
from
`employees`
) as `t`
on
`e`.`emp_no`=`t`.`e_n`
where
`t`.`r_num`%2=1 
