可以使用子查询进行筛选。假设你所说的第一行是指前面的那一行 start_time ，即：

select t.*
from mytable t
where t.start_time = (
    select min(t1.start_time) from mytable t1 where t1.call_unique_id = t.call_unique_id
)

from your_table t1
join
(
  select min(call_unique_id) as id
  from your_table
  group by start_time
) t2 on t1.id = t2.id
``` `group by` 我也应该做这项工作。所以试试看

select * from your_table group by call_unique_id