i took database back up on 01-jan-2005 and from 2nd jan onwards im taking differential backups. if i want to restore the database to a new system, is it sufficient that i restore the back up which i took on 1st jan , and the most recent differential backup ? will the entire data till the last back up date be restored?
I'm 99% sure that you'll need to restore the last full backup, plus each differential backup in sequence in order to get back to the state of the last differential dump you've got. In other words, if you are missing the backup from day 13 out of 30, you can only get to the point of the backup from day 12.
You only explicitly restore the last file, but all of the files need to be present in order for the restore to be successful.