can i run VB 6 or VB Net on Mac?

Oracle DB ... yes. In fact there are very few platforms that Oracle officially supports for its "full caffiene" products such as 11g DB and SOA. Enterprise Linux (RedHat and SUSE) and Mac are among them. Go to oracle.com, select "downloads" from the top menu an look for the maccompatible version.

MySQL is a different story ... no DMGs there, just a generic ".gz" to download and more complext instructions, but doable (I did it).

You can run Windows-based products such as .Net through BootCamp or VM (virtual machine) software that is hosting Windows 7.

Steve359 gave you most of the information. However I think you can use monodevelop to run .net

Good that someone knows the rest so the OP can be told.

Now we wait to see if the OP understands our responses.

HI Steve359,

I have removed almost all my pics, documents and movies and music from my mac. but it did not free much space. My HDD is only 250 GB but may valut shows 499GB. can you please help.

Best to open your own thread instead of redirecting (some may call it "highjacking") this one. Besides, a new one under the appropriate forum (SL or Lion) with a proper name would get more attention from the forum as a whole.