SQL & PL/SQL

When having to delete form a subquery (based on two unique identifiers) I concantenate the two columns to make them unique to an entry. Are there issues w/ this method and can any suggest something different (if any).


delete from ACCT_TEMP a where upper(a.id_name) || a.system_id in (
select upper(a.id_name) || a.system_id from ACCT_TEMP a, ACCT b
where upper(trim(both ' ' from a.id_name)) = upper(trim(both ' ' from b.account_name)) and a.system_id = b.system_id)