题解 | #给出表中排名为奇数行的first_name#

思路：①先排序，选出奇数行的first_name；②再进行一次子查询，从原表内选出前述first_name即可。
select first_name from employees
where first_name in (
select first_name from (
select first_name,
row_number()over(order by first_name) as r
from employees) as tb1
where r%2=1)