使用window函数尝试以下操作 row_number . 这是演示。

select
    coworker,
    date
from
(
    select
        *,
        row_number() over (partition by coworker order by date) as rn,
        count(*) over (partition by coworker) as ttl
    from myTable
) subq
where (ttl > 1 and rn = ttl - 1) or (ttl = 1 and rn = 1);

输出：

| coworker | date       |
| -------- | ---------- |
| 1        | 2019-09-12 |
| 2        | 2019-08-07 |
| 3        | 2018-06-24 |
| 4        | 2020-08-16 |

row_number() 功能可能有帮助：

select coworker, date 
from (
    select coworker, date, 
    count(*) over (partition by coworker) as count, 
    row_number() over (partition by coworker order by date desc) as order
    from MyTable
) t
where count = 1 OR (count > 1 and order = 2)