how does the MKLINK command work?

with reference to this article: Sync Files and Folders Outside Your My Dropbox Folder

i'm trying to backup files/databases which are always in sync - for example, my Evernote notebooks and my lightroom catalogs.

as such, i'm trying to understand the mechanics of MKLINK here. Let's say:

C:\Database = Original folder
F:\Dropbox\Database = Backup using MKLINK

Is it correct to say that the dropbox copy is an INERT file? That is to say, it remains purely as a backup and will never be used by the original app (be it Evernote, Lightroom or other apps that actively use their own databases) for syncing?

I'm asking because if it does use both the original and dropbox copies for syncing, there's a high chance my databases will be corrupted (as advised by Evernote).

would like to seek advice from the gurus here, thanks!

It is not a back up. Both folders point to the same storage area on the hard disk. In the original folder C:\Database where all data is physically stored in C: drive. Now if you make a link to F:\Dropbox\Database, then the folder F:\Dropbox\Database just point to the data stored in C:\Database. If you delete something in F:\Dropbox\Database or in C:\Database, it physically frees up the disk space in C:.

If it's not clear then please ask again.

EDIT: Add a screen shot:

yes i'd need to ask again.

the scenario is clear if both directory A and B are local storage areas. My question assumes that Directory B is in Dropbox. When the physical storage (in A) is mirrored in B (as u claim, not physically stored in B), I can access it freely via the Dropbox servers (i.e. web-based dropbox, or another computer).

does this mean it is backed up then?

Never under any circumstances will mklink copy or make a backup of any files. It simply allows a file or folder to appear in 2 locations at the same time. But there is never more then one copy of the file or folder, unless you create this by other means. Mklink is NOT a backup solution.