使用 SQL 进行序列编号

Question

I am attempting to sequence units by their arrival time within sql (adhoc) program. The only program uses calculation (sql script) to create a field. I have figured I would need to group by incident_number and sort by the earliest arrival_time

My thought is using sequence script, but I am unfamiliar if that would work.

Any thoughts?

Answer 1

What you are looking for is one of the window functions ROW_NUMBER , DENSE_RANK or RANK (depending on what you want to do in case of ties, if such can occur):

select
  incident_number,
  apperatus,
  alarm_date,
  arrival_date,
  row_number() over (partition by incident_number order by arrival_date) as sequence
from mytable
order by incident_number, arrival_date;

Answer 2

If you need to order by ascending arrival date with continuous sequence and same sequence number is assigned to multiple occurrences of same incident_number:

select incident_number, dense_rank() over(partition by incident_number order by 
arrival_date) as sequence_number from table;

If you need to order by descending arrival date with continuous sequence and same sequence number is assigned to multiple occurrences of same incident_number:

select incident_number, dense_rank() over(partition by incident_number order by 
arrival_date desc) as sequence_number from table;