How to get the latest two dates from table for each unique id

Question

unique_id	date
A	1/1/2023
A	3/1/2023
A	5/1/2023
B	1/1/2023
B	2/1/2023
B	3/1/2023
B	4/1/2023
C	1/1/2023

I want my data to look like this

unique_id	latest_date	2nd_latest_date
A	5/1/2023	3/1/2023
B	4/1/2023	3/1/2023
C	1/1/2023	Null

Answer 1

You could try using conditional aggregation and the row_number function as the following:

select unique_id,
       max(case when rn=1 then date end) as latest_date,
       max(case when rn=2 then date end) as _2nd_latest_date
from
(
  select *,
    row_number() over (partition by unique_id order by date desc) as rn
  from table_name
) T
group by unique_id
order by unique_id