As I have only ever worked with adults, I have not really had to deal with these issues. However, my friends who do teach take these things very seriously and are always trying to find answers because it is such a major problem. Teachers don't forget about prevention, but that is an area where they often have little control. Decisions taken at senior management level, by boards of governors, head teachers, etc, can often affect things like code of conduct, how well it is implemented. One complaint I have seen by many teachers is that they are over-ruled or that codes of conduct are not enforced, undermining their authority.
Have you read the TES forum on behaviour? It is worth reading some of the threads to see what teachers in the UK are having to deal with and how they try:
TES - Teaching jobs, resources & ideas from the Times Educational Supplement