Quick question: can I use composite primary keys?

[eluser]Unknown[/eluser]
Yes, the table's ID would be made of the values from two or three different columns. This would ensure that no duplicate columns are created and save the space of making an ID column. I know that CakePHP's ORM forbids you from using tables with composite keys, so I just wanted to make sure that CI could interface with database tables that have composite IDs.