I heard you can make it .mp4.

So, when the full backup was taken and while it's still available, the first differential backup became possible. And after the first differential backup was taken, subsequent differential backups can...

To take the first differential backup, what does SQL require? I mean does it require a full backup that it took earlier?

1. Thank you for confirmation!

2. I am afraid I didn't understand what you mean.

3. It's my bad. I apologise! The backup of 29 was full. But since it was deleted...