I've found a few query strings related to what I'm looking for, but nothing that does this. Basically, I have a graph that needs to display unique visitors per time interval (hour, day, month, or year). So, a graph similar to Google Analytics or this Analytics Graph. The table has a visitor ID column and a timestamp column (in the style 0000-00-00 00:00:00). I need to be able to select the unique or total visitors per interval (eg. 32 visitors on the 5th, 30 on the 6th, etc).
I guess my question is, is there anyway to do this efficiently with just a query? Or will I need to use PHP to get all the data (problem with that is that I would have to do a query for each point on the graph, not efficient)?