I wouldn’t touch the database… I’d use the API to copy threads  to the new discussion  list.

Have you looked at possibly exporting the discussion list to an Excel list and importing it into the new list? I have no idea if this would work… just a guest because it’s just a list.

querying the database  is a big risk. I wrote a web part to copy the threads, but its showing new modified date and new Posted By, i.e. not preserving the meta data, and I'm not able to move  the attachments  programmatically.

I didn't see the option to export discussion  threads to an Excel list but for a custom list exporting to Excel and importing again displays new dates, created by etc.

Any other thoughts how this can be done, without querying the database?

When you say metadata, you’re referring to the fields like “created by”, “modified date”, etc… correct? Why can’t you access them? Out of curiosity, why do this in a Web Part? I would think it would be much easier doing this with a console app or something of the like. You should be able to obtain the attachments… are you saying it’s not possible or that you’re having trouble getting it to work?

The Excel thing was a shot in the dark… worth a shot though!

I’m sure this can be done without querying the DB.

yes, it is possible to copy attachments, infact I saw the sample code in msdn, it's just I'm not smart enough to do it right now. I'm working on it.

The web part copies the threads  to a new discussion  board, but displays new created by(current user) and new "modified", "Posted By" etc as if I'm adding a new discussion item.

Maybe I'll have to get these fields information from the source discussion board  and set it to the destination discussion board.

I don’t believe this is possible. The new threads  will have new metadata, all based on the person moving over the threads unless you do a manual move  post by post to keep them in order and whatnot (still lose poster info).

I know what ever I do, it will show up under new name with new date etc. but it's difficult to explain the clients.

Following might be helpful weblogs.asp.net/.../385523.aspx