- Check, recheck, and check again any statment that is doing updates. Even if you think you're just doing a simple, single column update, sooner or later you will not have enough coffee and forget a 'where' clause, nuking a whole table.
A couple other things I've found helpful:
if using MySQL, enable Safe updates
If you have a DBA, ask them to do it.
I 've found these 3 things have kept me from doing any serious harm.
