Duplicated records

Hi.
How can I delete the duplicated records with "DELETE FROM TABLE WHERE..."
clause??
The problem is becouse I have imported data from Dbase (dbf) file, and this
function have not built the Constraint (unique, primary key, ...), and this
function is usually executed.
select * from table1; --id may be primary key- Table1 -id | field 20  | 'aaa'1  | 'bbb'2  | 'ccc'0  | 'aaa'  <<== The
datais duplicated1  | 'bbb'2  | 'ccc'0  | 'aaa'1  | 'bbb'2  | 'ccc'
 
Is there a way to delete the duplicated data without build another table with
constraints and copy those data to the new table?
Something like "delete from table1 where ...???"

Thanks,
Lucas