Remove duplicate rows in a table

Question

I have a table contains order information like below:

Order table:

As we can see from that table, each order_no has several duplicates. So what I want is to keep only one row for each order_no (no matter which one it is)

Is anyone knows how to do this? (FYI, I am using Oracle 10)

Answer 1

This should work, even in your ancient and outdated Oracle version:

delete from order_table
where rowid not in  (select min(rowid)
                     from order_table
                     group by order_no);

Answer 2

If you don't care which row you get for each order_no, perhaps the simplest solution (before Oracle 12) is:

select [whatever columns you want, probably not rn - see below]
from ( select order_table.*,
              row_number() over (partition by order_no order by null) as rn
     )
where rn = 1
;