Start from here:
http://en.wikipedia.org/wiki/Concurrency_control[
^].
Read it to get the ideas and terminology. The question of samples makes no sense, because the topic is too big: it is impossible to make reasonably limited number of definitive samples even for most important cases. You need to decide what are you interested in first.
As you learn concepts and terminology, finding samples would not be a problem. Google is your friend (I hope) :-).
—SA