Unique table entries

I was wondering if anyone could help with an ACE and SQL problem. I need to query a equipment table for duplicate fields and fields with partial duplicate date and can't seem to find the right commands. I would like to query the equipment table for duplicate serial numbers and then check to see if the model number is > 6 characters and delete the duplicates. Then, with the fields that are > 6 chars, I need to clip the field using an UPDATE command if possible. I actually just wanted to print a copy of what I would be deleting (using ACE) and then run the SQL script. I am new to Informix SQL and really appreciate any help, P.S. I am using an old version of Informix - 2.10 Thanks alot, Brian brianr@magnus1.com