More than one router

[God Emperor Baldur]

So here is a scenario that I have been playing out. In terms of my networking skill, I guess you could call it A+ level along with several trade secrets I know of to make use of it. However, there is one things I always wanted to know. Let's say that a company has a network for their point of sales, printers, office computers and all that jazz, but they also want to give their customers free wifi. Now in terms of connecting the wifi router up, I could just set it up to work on the subnet and disable the DHCP on the router. There you have an internet hub, but it's also a security issue because anyone can just type in the router ip and they can do as they please. So I want to know. Is there a way for the wifi router to have its own DHCP and work in a bridged manner?

[Sonic Offline]

Well likely what they do is either it's entirely it's own network that's not attached to the PoS network, or it's running into the same sever in the back and the two networks are on their own scopes, making them two virtually unconnected networks.