The distinction between the two, database marketing and networking, is that people in the database do not receive personal contact with you. You do not contact them personally on any regular basis. You probably do not use their services and you most likely do not know them well enough to refer them to members of your network. A database is a one way street. You simply use the names and addresses to send information and market your services.
Many business people find it useful to use some type of database marketing.
It can be a useful tool, however it does not take the place of a strong network. The truth is there are only so many people that one could realistically have in their network. A person that has a database of thousands of people cannot possibly contact all of them personally, or even know most of them. Some people may have a network with as few as ten to fifteen people, others may be able to handle a network of two hundred people. There is no magic number, it is whatever you can conformably manage.