Dedup my table

Question

I have a row that shows playtimes for videos. Our app has a bug that allowed duplicate rows. Technically on the db they aren't duplicate because the id's are unique but they have the same asset_num and start_times. I need to weed out all the rows with duplicate asset_num and start_times BUT i need to keep one of the duplicates.
I run this to get which rows have more than 1 row:
select asset_id, start_time, count(*) from current_schedule group by asset_id, start_time order by count(*) desc
Each row also has a unique id that i could use in the delete statment but i want to leave ONE of the rows after my delete.
Has anyone ever dedup a table like this? I think i need a delete statement based on rowid but i haven't been able to get it to work yet. Any help would be greatly appreciated.

Answer 1

this example might be of help.
SQL> select * from employees;
YEAR EM NAME       PO
2001 02 Scott      91
2001 02 Scott      01
2001 02 Scott      07
2001 03 Tom        81
2001 03 Tom        84
2001 03 Tom        87
6 rows selected.
SQL> select year, empcode, name, position,
  2         row_number() over (partition by year, empcode, name
  3                            order by year, empcode, name, position) as rn
  4    from employees;
YEAR EM NAME       PO         RN
2001 02 Scott      01          1
2001 02 Scott      07          2
2001 02 Scott      91          3
2001 03 Tom        81          1
2001 03 Tom        84          2
2001 03 Tom        87          3
6 rows selected.
SQL> Select year, empcode, name, position
  2    From (Select year, empcode, name, position,
  3                 row_number() over (partition by year, empcode, name
  4                                    order by year, empcode, name, position) as rn
  5            From employees) emp
  6   Where rn = 1;
YEAR EM NAME       PO
2001 02 Scott      01
2001 03 Tom        81
SQL> Delete From employees
  2   Where rowid in (Select emp.rid
  3                     From (Select year, empcode, name, position,
  4                                  rowid as rid,
  5                                  row_number() over (partition by year, empcode, name
  6                                            order by year, empcode, name, position) as rn
  7                             From employees) emp
  8                    Where emp.rn > 1);
4 rows deleted.
SQL> select * from employees;
YEAR EM NAME       PO
2001 02 Scott      01
2001 03 Tom        81
SQL>