There is nothing "official" about private university records. If you want to know whether someone matriculated at a given college, all you have to go on is the word of the administration. Transcripts, diplomas, etc. are just the word of the administration put down on paper. That's why the testimony of an administrator would be perfectly acceptable evidence in court that a given person attended a college.
Administrators from Columbia and Occidental have both said Obama was a matriculated student there, and Columbia has confirmed he recieved a degree. That would be good enough in any court, unless you have some evidence to the contrary.
Heresay, heresay, heresay....from Obama insiders. Yeah, you just keep believeing in the tooth fairy too.