Best practice to keep RSS feeds unique in sql database

I am working on a project which shows rss feeds from different sites.I keep them in the database, every 3 hours my program fetches and inserts them into sql database.I want unique records for providers not to show duplicate content.

But problem is some providers do not give GUID field, and some others gives GUID field but not pubdate.. And some others does not even give GUID or PubDate just title and link.

So to keep rss feeds uniqe in sql server what would be the best way?

Should I check for first guid, then pubbdate, then link, then title? Will it be to good practice to compare link fields in SQL to check uniqueness?

Thanks.