You could have 100 "sites" pointing to ONE database but the principle will remain...

... it's still ONE database, so whatever you add to, or subtract from it will be common to all 100 "sites" (ie: front-ends).

It appears that you do not fully understand the principle of dyanmic content websites. There are some good online tutorials which you should do.

... besides, it's very risky running one dbase through several "sites".

Look at the multisite module if you want a proper way of doing this.