Have you ever used AJAX? Where the browser uses the XMLHTTP object to communicate with the server?
Well, servers can do the same thing. And the best part is that server side code is *NOT* restricted to the same domain.
So... The question now is, what server-side technology are you using or going to use? PHP? ASP? JSP?
And now go ask your question in the appropriate forum. (I know how to do it in ASP and JSP, for example, but I don't use PHP.)
As for importing into MySQL (I assume you are giong to use MySQL since you asked in a MySQL forum?), that's *probably* easy if you use MySQL's LOAD DATA INFILE
It can handle most CSV formats.