I was working full time and did my PhD at the same time. My employer let me do the work at work (there was a lot of overlap) and only had to travel to university to take a few classes (made up the time by working longer hours and sometimes on weekends) and meet with my academic advisor. I also had an advisor (mentor) at work that I would interact with on a daily basis. The downside was that I had to pay tuition, but the company paid for some and the rest I paid from my salary. I still made more than a graduate student at the institution. Overall, it was a great experience. I would recommend doing it this way if you are interested in going into industry and you already have a built-in job. I was upfront when I got hired and told them I was looking to do a PhD and they agreed.