yet another simple SQL question

Ok,

You guys must be getting sick of these newbie questions, but I can't
resist since I am learning a lot from these email lists and getting
results quick! Thanks to everyone for their contributions.

Here is my questions....

I have a column that looks like this

firstname
-----------------
John B
Mark A
Jennifer D

Basically I have the first name followed by a middle initial. Is there a
quick command I can run to strip the middle initial? Basically, I just
need to delete the middle initial so the column would then look like the
following:

firstname
---------------
John
Mark
Jennifer

Thanks again for all of your help today. Everything you guys have been
sending has produced successful results.

Thanks.