Hmm, I'd test it myself if i was on windows, but "system clear" works on OS X and Linux, and if I recall correctly, the command to clear window is "cls" in Windows
There is a number of solutions in Linux like this one, but the consensus seems to be there is none for Windows. See e.g. here or here (scroll to the bottom)
That Yahoo! Answer is a very stupid one IMO. The mySQL console is there for a purpose. I'm tempted to open a Yahoo account just in order to leave a comment to that effect.