There are a number of open source toolkits that you can tailor to create your own social networking site. Popular systems are Wordpress, Drupal and Elgg. How much work is involved depends on your target audience:
advogato stands out as a ten year old site for free software developers that has been functional as a social networking site for its target audience. Such a site is well within the scope of a single developer to create and manage.
Quote:
Originally Posted by tobyhede  Um, where was I. As a database MySQL is used to store all the data with the exception of files (such as images). So all profile data will be stored in MySQL. |
This is right, but could do with a bit of explanation: the database should hold all data that can change as a result of user interaction with the system. This is needed because websites deal with users in a parallel manner, and this risks data corruption if data changes are not handled properly. The database knows how to do this.
Check out Greenspun's classic
Database-backed web sites for information that every web developer should be on top of.