Stanton Schmidt schrieb am 08.03.2018 um 19:58:
> My question is:
> I have a table that has log events for pieces of equipment. For each piece of equipment this table may contain 1 or
more(hundreds potentially).
> I need to write a query that will return only the last 5 log events for each (and every) piece of equipment.
>
> log_table (
> equipment_id character(30),
> log_date date,
> log_time time,
> event_desc text
> )
Queries like that are typically solved using window functions:
select *
from (
select equipment_id,
log_date,
log_time,
event_desc,
row_number() over (partition by equipment_id order by log_date desc, log_time desc) as rn
from log_table
) t
where rn <= 5;
Unrelated, but: why aren't you storing "log_date_time" in a single timestamp?
