SQL & PL/SQL

Hi all,

Trying to solve next issue with lead/lag functions:

Got table s09:

I need to group ordered by start_date rows by guid into one group if start_date-1 of current row equals to end_date of previows row.

The result I need:

I try to solve this with lead/lag functions:

select case

            when lag(w1.end_date, 1, w1.end_date) over (order by w1.guid, w1.start_date)=w1.start_date-1

            then lag(w1.start_date,1, w1.start_date) over (order by w1.guid, w1.start_date)

            else w1.start_date

             and first_start_date,

             w1.end_date

      from s09

This works only for first two rows..

Third row will get start_date of 2nd row.

What functoin can hold start_date of first row in the group for all rows, that satisfy condition: start_date-1 of currentt row=end_date of prev row of the group?

Any suggestions what function will help?

Thanks for any answers!