Question : Need to Flag duplicate records

I have a file of 10,000 records about 70 of those are duplicates. I added a column to by used as a flag. How do I mark that column using sql?  mahalo

Update Table
set flag = 1
where id in  ?  

Answer : Need to Flag duplicate records

Yes this happens all the time.  Its called NAT or PAT depending on what you are doing.  Typically a firewall implements this function and it NAT (network address translation)  or PAt (port address translation) depending on your needs.