How to Retain a Fresher?

Many a times the freshers when they come in within six months, one year after you train they leave. We are thinking of looking at some kind of a retainer ship at least three years. So that's why I was just trying to figure out how do we do this? The world of business has seen three generations. Industrial revolution people took a job for survival. They wanted basic necessity of roti kabatam kana. That is pretty much the grandparents of today's workforce.