One database is necessary for a forums it can be IBM DB2 or Open source Mysql or Oracle or Microsoft's sql server 2008 or Post Gre. And you need one server side language to connect it. X10hosting.com provides PHP as it is open source. And they also give mysql and postgre databases. Either you can desingn forum using that.
or install a forum from fantasico
phpBB or SMF
just one or two click will do.
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My site is
http://klnce.elementfx.com