Question about deleting table duplicates

I was looking for thw SQL to delete dupes from a table, and came across this. All who saw it agreed in principle, but I can't quite figure out the logic. If we are deleting all rows whose rowid is greater than the least of the rowids returned from creating the subset of dupes, couldn't we inadvertently delete some non-dupes rows that were created after the last dupe ? I mean, any row created after the last dupe would have a greater rowid, wouldn't it ?

Here's the SQL:

delete from table_1 a
where a.rowid >

   (select min(b.rowid)
    from table_1 b
    where b.col_dup_values = a.col_dup_values)

By the way, should the delete ALL dupes, including the originals ? That is all rows participating in duplicity, as it is, will be gone.

Thanks,
Scott Received on Thu Sep 18 2003 - 19:07:17 CEST