mysql error in retrieving data

I have data in my webpage that is coming from MySQL. Its a field that is initially zero and increases in value as the users visits more pages, it counts them and writes the tracked value to a cell on the pages.

But the开发者_Python百科 problem is it works fine for few weeks then suddenly it again starts from zero. Can somebody tell me what should I do?

My MySQL column definition is:

column name page_view type INT Length/values 255 Default None