This is one good reason why I never go out to drink. If I get even slightly impaired, I want it to be at home, where it won't matter as much.
It's also a very good reason to carry a firearm---if you legally can, and have practiced using it in a defensive manner, (there are plenty of classes that teach that, as well as all the legal implications of pulling or even carrying a firearm). Not when you're drunk of course, then it could only hurt, but you shouldn't be drunk in public anyway.
I've seen a lot of these mass assaults in the news recently; they seem to be getting more and more common over the last few years.