Oracle SQL Cursor for循环，用于在START_DATE和END_DATE之间检查并分配行程值

Question

I'm using SQL Developer for Oracle 11g..

I need to be able to loop through a set of dates, check to see if the END_DATE above or below is = or < or > than the next END_DATE AND where the START_DATE is different..

Then assign a trip number that is the same as the one its = to or assign a new trip number and then begin a new trip and check again the next SET of dates to see if its = or < or > than the current date..

I think in order to do this I need to use the pl/sql cursor for loop.. I've tried to figure it out but its not making much sense to me..

For example, I want the end result to be something like this..

ROWID   START_DATE END_DATE   TRIP
  1         30-DEC-11  1-Jan-12 1
  2         31-DEC-11  2-Jan-12 2
  3         31-DEC-11  2-Jan-12 2
  4         01-JAN-12  3-Jan-12 3
  5         03-JAN-12  4-Jan-12 4
  6         01-JAN-12  1-Jan-12 5
  7         02-JAN-12  4-Jan-12 6

Thanks in advance for your help. Alex

Answer 1

Based on the data that you have, you simply want to enumerate the pairs of dates. You can also do this with dense_rank():

select t.*,
       dense_rank() over (order by start_date, end_date) as trip
from t

For your data, this will change the ordering. If you want to keep roughly the same ordering, then aggregate first, get the min row id, and do a dense_rank() or row_number(), and join back in the original data:

select t.*, trip
from (select start_date, end_date, row_number() over (partition by row_id) as trip
      from (select start_date, end_date, min(rowid) as rowid
            from t
            group by start_date, end_date
           ) a
     ) b join
     t
     on b.start_date = t.start_date and b.end_date = t.end_date