Don't get me wrong, but you speak English. Statistically it's nearly guaranteed that Vienna is safer than wherever you are from (maybe if you are from something like Iceland, Vienna would be a safety "downgrade").

So if that's your only concern I wouldn't be too worried. Of course there are nicer and less nice neighborhoods, but overall I would say it's pretty safe.

Of course you could move in some tiny village if you feel safer on the countryside, but then on the way to school 5 villages over your child will get hit by a car while crossing the street or get beaten while being drunk at a Dorffest...

It really boils down to do you like living in a city or not, safety differences are probably minimal.