自用题解

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