Oracle - deleting duplicates

Question

I have found the following way for removing duplicates:

DELETE FROM
   table_name A
WHERE
  a.rowid >
   ANY (
     SELECT
        B.rowid
     FROM
        t         


        

Answer 1

In Oracle, ROWID is a pseudo column points to the physical location of a row. The query does a self join and fetches those rows which have the same value of column 1 & column 2 - with the assumption that these keys are enough to identify as duplicate row.

Once the rows are fetched, the query then deletes those rowids which are larger than the first row fetched, thereby deleting duplicates