A "newbie" with just 2 posts had two posts deleted by the automatic SPAM killer because he included URLs in his post. I do wish they'd fix that somehow although it will be difficult. In the meantime, here's the post that person posted. And, welcome aboard, Mick. Don't let this temporary problem prevent you from posting. I'd just avoid posting anything that looks like a URL until your post count goes up a bit (and, no, I don't know what the magic number is).
davismick643
Differential backups are a type of backup which stores the changes which have occurred in your database since the last FULL database backup. In order to be able to create a differential backup you will need to have a FULL database backup before. Multiple differential backups can be created later, which store the incremental changes in your database since your last FULL or DIFFERENTIAL backup, but having a FULL backup is mandatory as this is the base for your later backups which are of a different type(differential or transaction log). I can propose a few articles to you.1. https://technet.microsoft.com/en-us/library/ms190412%28v=sql.105%29.aspx
2. http://sqlbak.com/blog/cannot-perform-a-differential-backup/
Hope that will be useful
--Jeff Moden
Change is inevitable... Change for the better is not.